Knowledge

Circle

Source 📝

156: 6067: 1795:
visual art to convey the artist's message and to express certain ideas. However, differences in worldview (beliefs and culture) had a great impact on artists' perceptions. While some emphasised the circle's perimeter to demonstrate their democratic manifestation, others focused on its centre to symbolise the concept of cosmic unity. In mystical doctrines, the circle mainly symbolises the infinite and cyclical nature of existence, but in religious traditions it represents heavenly bodies and divine spirits.
1599: 3475: 2321: 5743: 5437: 2989: 7141: 49: 5950: 1538: 1528: 5767: 1775: 1912: 1610: 3470:{\displaystyle {\frac {({\color {green}x}-x_{1})({\color {green}x}-x_{2})+({\color {red}y}-y_{1})({\color {red}y}-y_{2})}{({\color {red}y}-y_{1})({\color {green}x}-x_{2})-({\color {red}y}-y_{2})({\color {green}x}-x_{1})}}={\frac {(x_{3}-x_{1})(x_{3}-x_{2})+(y_{3}-y_{1})(y_{3}-y_{2})}{(y_{3}-y_{1})(x_{3}-x_{2})-(y_{3}-y_{2})(x_{3}-x_{1})}}.} 1502:: one of the two possible arcs determined by the endpoints of a diameter, taking its midpoint as centre. In non-technical common usage it may mean the interior of the two-dimensional region bounded by a diameter and one of its arcs, that is technically called a half-disc. A half-disc is a special case of a segment, namely the largest one. 1406:: a line segment whose endpoints lie on the circle and that passes through the centre; or the length of such a line segment. This is the largest distance between any two points on the circle. It is a special case of a chord, namely the longest chord for a given circle, and its length is twice the length of a radius. 1798:
The circle signifies many sacred and spiritual concepts, including unity, infinity, wholeness, the universe, divinity, balance, stability and perfection, among others. Such concepts have been conveyed in cultures worldwide through the use of symbols, for example, a compass, a halo, the vesica piscis
1794:
From the time of the earliest known civilisations – such as the Assyrians and ancient Egyptians, those in the Indus Valley and along the Yellow River in China, and the Western civilisations of ancient Greece and Rome during classical Antiquity – the circle has been used directly or indirectly in
7322: 6625:
is the case in which the weights are equal. A circle is an ellipse with an eccentricity of zero, meaning that the two foci coincide with each other as the centre of the circle. A circle is also a different special case of a Cartesian oval in which one of the weights is
6754:
is a figure whose width, defined as the perpendicular distance between two distinct parallel lines each intersecting its boundary in a single point, is the same regardless of the direction of those two parallel lines. The circle is the simplest example of this type of
5166:
Through any three points, not all on the same line, there lies a unique circle. In Cartesian coordinates, it is possible to give explicit formulae for the coordinates of the centre of the circle and the radius in terms of the coordinates of the three given points. See
7458: 2834: 6784:
points in the plane. The locus of points such that the sum of the squares of the distances to the given points is constant is a circle, whose centre is at the centroid of the given points. A generalization for higher powers of distances is obtained if under
4025: 7023: 4429: 2652: 6709: 7660: 1691:
A circle is a plane figure bounded by one curved line, and such that all straight lines drawn from a certain point within it to the bounding line, are equal. The bounding line is called its circumference and the point, its
7174: 2074: 4709: 7331: 3721: 4920: 2696: 6563:, passing through each vertex. A well-studied example is the cyclic quadrilateral. Every regular polygon and every triangle is a cyclic polygon. A polygon that is both cyclic and tangential is called a 5754:(red). Hence, all inscribed angles that subtend the same arc (pink) are equal. Angles inscribed on the arc (brown) are supplementary. In particular, every inscribed angle that subtends a diameter is a 5322:
The sum of the squared lengths of any two chords intersecting at right angles at a given point is the same as that of any other two perpendicular chords intersecting at the same point and is given by 8
4322: 6481: 5061: 2978: 5721: 4208: 1424:: a line segment joining the centre of a circle with any single point on the circle itself; or the length of such a segment, which is half (the length of) a diameter. Usually, the radius is denoted 5852: 4819: 1412:: the region of the plane bounded by a circle. In strict mathematical usage, a circle is only the boundary of the disc (or disk), while in everyday use the term "circle" may also refer to a disc. 2701: 2569: 7059:, the loci of the constant sums of the second and fourth powers are circles, whereas for the square, the loci are circles for the constant sums of the second, fourth, and sixth powers. For the 6212: 5864:, since the sagitta intersects the midpoint of the chord, we know that it is a part of a diameter of the circle. Since the diameter is twice the radius, the "missing" part of the diameter is ( 5558:
The angle between a chord and the tangent at one of its endpoints is equal to one half the angle subtended at the centre of the circle, on the opposite side of the chord (tangent chord angle).
3582: 5953:
Construct a circle through points A, B and C by finding the perpendicular bisectors (red) of the sides of the triangle (blue). Only two of the three bisectors are needed to find the centre.
2296: 1486:: a region bounded by a chord and one of the arcs connecting the chord's endpoints. The length of the chord imposes a lower boundary on the diameter of possible arcs. Sometimes the term 2458: 1993: 5653: 5621: 3899: 3910: 2161: 6905: 6349: 4991: 1720:
there is a detailed definition and explanation of the circle. Plato explains the perfect circle, and how it is different from any drawing, words, definition or explanation. Early
8645: 2544: 7694:
parallel to the coordinate axes, so planar Chebyshev distance can be viewed as equivalent by rotation and scaling to planar taxicab distance. However, this equivalence between
1902: 8053: 3798: 2564: 7499: 6506:
satisfying the above equation is called a "generalised circle." It may either be a true circle or a line. In this sense a line is a generalised circle of infinite radius.
4140: 3759: 2229: 6747:
is a set of points such that the product of the distances from any of its points to two fixed points is a constant. When the two fixed points coincide, a circle results.
5875:) in length. Using the fact that one part of one chord times the other part is equal to the same product taken along a chord intersecting the first chord, we find that ( 7592: 7587: 4090: 5341:
The distance from a point on the circle to a given chord times the diameter of the circle equals the product of the distances from the point to the ends of the chord.
7050: 6880: 6830: 7535: 4327: 1480:: a region bounded by two radii of equal length with a common centre and either of the two possible arcs, determined by this centre and the endpoints of the radii. 7164:
Defining a circle as the set of points with a fixed distance from a point, different shapes can be considered circles under different definitions of distance. In
1468: 8201: 6853: 6900: 6803: 6782: 2087:
The circle is the plane curve enclosing the maximum area for a given arc length. This relates the circle to a problem in the calculus of variations, namely the
2004: 1442: 2474:
applied to any point on the circle: as shown in the adjacent diagram, the radius is the hypotenuse of a right-angled triangle whose other sides are of length |
8623: 8123: 6636: 4571: 1284: 8421: 3625: 4839: 1941:
is equal to that of a triangle whose base has the length of the circle's circumference and whose height equals the circle's radius, which comes to
7154:-norms (every vector from the origin to the unit circle has a length of one, the length being calculated with length-formula of the corresponding 6574:
is a curve that is inscribed in a given circle by tracing a fixed point on a smaller circle that rolls within and tangent to the given circle.
6386: 4996: 8311: 5908: 4147: 1733: 384: 7830: 6525:
About every triangle a unique circle, called the circumcircle, can be circumscribed such that it goes through each of the triangle's three
6519: 5796: 2862:
is made to range not only through all reals but also to a point at infinity; otherwise, the leftmost point of the circle would be omitted.
4714: 6154: 5188:
of a chord passes through the centre of a circle; equivalent statements stemming from the uniqueness of the perpendicular bisector are:
7317:{\displaystyle \left\|x\right\|_{p}=\left(\left|x_{1}\right|^{p}+\left|x_{2}\right|^{p}+\dotsb +\left|x_{n}\right|^{p}\right)^{1/p}.} 7092: 5914:
The simplest and most basic is the construction given the centre of the circle and a point on the circle. Place the fixed leg of the
5793:
of the sagitta, the Pythagorean theorem can be used to calculate the radius of the unique circle that will fit around the two lines:
3495: 8705: 8278: 350: 5211:
of a circle are subtended by the same chord and on the same side of the chord, then the central angle is twice the inscribed angle.
2252: 1344:, makes much of modern machinery possible. In mathematics, the study of the circle has helped inspire the development of geometry, 8050: 8540: 8159: 1603: 4231: 2383: 1948: 8002: 2873: 2855: 3851: 8672: 5658: 2130: 1277: 1231: 837: 296: 105: 8521: 8182: 7453:{\displaystyle \left\|x\right\|_{2}={\sqrt {\left|x_{1}\right|^{2}+\left|x_{2}\right|^{2}+\dotsb +\left|x_{n}\right|^{2}}}.} 5856:
Another proof of this result, which relies only on two chord properties given above, is as follows. Given a chord of length
8075: 6290: 5354:
A line drawn perpendicular to a tangent through the point of contact with a circle passes through the centre of the circle.
1378:
part of a circle. Specifying two end points of an arc and a centre allows for two arcs that together make up a full circle.
8732: 5351:
A line drawn perpendicular to a radius through the end point of the radius lying on the circle is a tangent to the circle.
5116: 4934: 7987: 8502: 2493: 1787: 8120: 5521:
A tangent can be considered a limiting case of a secant whose ends are coincident. If a tangent from an external point
5357:
Two tangents can always be drawn to a circle from any point outside the circle, and these tangents are equal in length.
8727: 8393: 8198: 8027: 6583: 5253: 3607: 2353: 7768: 2829:{\displaystyle {\begin{aligned}x&=a+r{\frac {1-t^{2}}{1+t^{2}}},\\y&=b+r{\frac {2t}{1+t^{2}}}.\end{aligned}}} 1863: 3815: axis to the line connecting the origin to the centre of the circle). For a circle centred on the origin, i.e. 8817: 6357:
is a point on the circle of Apollonius if and only if the cross-ratio is on the unit circle in the complex plane.
1252: 862: 5782:) is a line segment drawn perpendicular to a chord, between the midpoint of that chord and the arc of the circle. 4097: 1508:: a coplanar straight line that has one single point in common with a circle ("touches the circle at this point"). 1332:
The circle has been known since before the beginning of recorded history. Natural circles are common, such as the
2202: 1736:, and many believed that there was something intrinsically "divine" or "perfect" that could be found in circles. 1270: 8593: 1321:. The length of a line segment connecting two points on the circle and passing through the centre is called the 8780: 7788: 7666: 7085: 6537: 5072: 4925: 4444: 3587: 2847: 2088: 1567: 1471: 239: 5626: 5594: 4050: 8822: 8457: 7885: 7084:, of constructing a square with the same area as a given circle by using only a finite number of steps with 6751: 5750:
An inscribed angle (examples are the blue and green angles in the figure) is exactly half the corresponding
5737: 5247:
Among all the circles with a chord AB in common, the circle with minimal radius is the one with diameter AB.
3485: 1934: 1740: 1729: 665: 345: 202: 31: 7875: 6607: 6137: 6000: 5985: 5915: 5185: 2558: 1598: 741: 452: 330: 215: 2307:, these formulae yield the circumference of a complete circle and area of a complete disc, respectively. 8639: 8244: 7992: 7982: 7735: 7100: 6066: 6061: 5109: 4431:. Not all generalised circles are actually circles: a generalised circle is either a (true) circle or a 1838: 1748: 1361: 513: 474: 433: 428: 281: 7734:. Two topological circles are equivalent if one can be transformed into the other via a deformation of 8269:
Abdullahi, Yahya (29 October 2019). "The Circle from East to West". In Charnier, Jean-François (ed.).
1130: 877: 8433: 7977: 7056: 5225: 5218: 5214:
If two angles are inscribed on the same chord and on the same side of the chord, then they are equal.
1705: 1701: 1681: 1181: 1104: 952: 857: 379: 274: 188: 5945:
passing through one of the endpoints of the diameter (it will also pass through the other endpoint).
8007: 7078: 7072: 6499: 6090: 5083: 5079: 3764: 2659: 2554: 2471: 2169:
the angle at the centre of the circle. The angle subtended by a complete circle at its centre is a
1808: 1752: 1310: 1186: 1043: 897: 802: 692: 563: 553: 416: 291: 286: 269: 244: 232: 184: 179: 160: 7477: 155: 8605: 8574: 8449: 8344: 8103: 7942: 7912: 7763: 7758: 7677: 7108: 6533: 6366: 5775: 4225: 3732: 3586:
It can be proven that a conic section is a circle exactly when it contains (when extended to the
1779: 1409: 1326: 1145: 872: 712: 340: 264: 254: 225: 210: 5238: 5217:
If two angles are inscribed on the same chord and on opposite sides of the chord, then they are
4020:{\displaystyle r=r_{0}\cos(\theta -\phi )\pm {\sqrt {a^{2}-r_{0}^{2}\sin ^{2}(\theta -\phi )}}.} 8791: 7540: 6283:
are as above, then the circle of Apollonius for these three points is the collection of points
8751: 8701: 8668: 8470: 8307: 8303: 8296: 8274: 8095: 7895: 7870: 7018:{\displaystyle \sum _{i=1}^{n}d_{i}^{2m}>nR^{2m},\quad {\text{ where }}~m=1,2,\dots ,n-1;} 6564: 6526: 5158: 4931:
When the centre of the circle is at the origin, then the equation of the tangent line becomes
3619: 2357: 2104: 1835: 1763: 1381: 1314: 1216: 1206: 1135: 1004: 982: 932: 907: 842: 766: 421: 313: 259: 220: 7474:
with sides oriented at a 45° angle to the coordinate axes. While each side would have length
4424:{\displaystyle |z-c|^{2}=z{\overline {z}}-{\overline {c}}z-c{\overline {z}}+c{\overline {c}}} 1390:: a line segment whose endpoints lie on the circle, thus dividing a circle into two segments. 8812: 8722: 8615: 8566: 8441: 8354: 8087: 7930: 7860: 7783: 7502: 7463: 7104: 7060: 6545: 6259:
Second, see for a proof that every point on the indicated circle satisfies the given ratio.
6105:. (The set of points where the distances are equal is the perpendicular bisector of segment 5587:
If two secants are inscribed in the circle as shown at right, then the measurement of angle
5445: 5091: 2320: 1924: 1762:
in the early 20th century, geometric objects became an artistic subject in their own right.
1655:, dated to 1700 BCE, gives a method to find the area of a circle. The result corresponds to 1490:
is used only for regions not containing the centre of the circle to which their arc belongs.
1483: 1387: 1306: 1196: 937: 647: 525: 460: 318: 303: 168: 110: 8366: 7028: 6858: 6808: 6093:
showed that a circle may also be defined as the set of points in a plane having a constant
5181:
Chords are equidistant from the centre of a circle if and only if they are equal in length.
1841:
approximately equal to 3.141592654. The ratio of a circle's circumference to its radius is
8544: 8525: 8506: 8362: 8205: 8186: 8154: 8139: 8127: 8057: 7925: 7803: 7798: 7741: 7717: 7520: 7116: 6591: 6549: 5208: 5123: 4432: 2238: 1477: 1415: 1375: 619: 492: 482: 325: 308: 249: 1447: 1191: 1160: 1094: 1064: 942: 887: 882: 822: 8437: 8076:"Sacred landscapes of the south-eastern USA: prehistoric rock and cave art in Tennessee" 8074:
Simek, Jan F.; Cressler, Alan; Herrmann, Nicholas P.; Sherwood, Sarah C. (1 June 2013).
6835: 5918:
on the centre point, the movable leg on the point on the circle and rotate the compass.
5742: 8694: 8557:
Apostol, Tom; Mnatsakanian, Mamikon (2003). "Sums of squares of distances in m-space".
7972: 7890: 7865: 7850: 7835: 7808: 7778: 7773: 6885: 6788: 6767: 6614: 6556: 6541: 6522:, can be inscribed such that it is tangent to each of the three sides of the triangle. 6145: 5562: 5229: 5087: 2490:|. If the circle is centred at the origin (0, 0), then the equation simplifies to 2181: 2170: 1938: 1717: 1641: 1559: 1427: 1247: 1221: 1155: 1099: 972: 852: 832: 812: 717: 8537: 5436: 5078:
The circle is a highly symmetric shape: every line through the centre forms a line of
2647:{\displaystyle {\begin{aligned}x&=a+r\,\cos t,\\y&=b+r\,\sin t,\end{aligned}}} 8806: 8661: 8107: 7962: 7855: 7731: 6704:{\displaystyle \left|{\frac {x}{a}}\right|^{n}\!+\left|{\frac {y}{b}}\right|^{n}\!=1} 6621:
of the distances from any of its points to two fixed points (foci) is a constant. An
5751: 5199: 4036: 3489: 2246: 1825: 1783: 1652: 1637: 1629: 1571: 1393: 1226: 1211: 1140: 957: 917: 867: 642: 605: 572: 410: 406: 98: 8578: 8358: 7119:
coefficients. Despite the impossibility, this topic continues to be of interest for
8795: 8570: 8453: 7880: 7145: 7140: 7063:
the constant sum of the eighth powers of the distances will be added and so forth.
6744: 6630: 6618: 6560: 5285:
If the intersection of any two perpendicular chords divides one chord into lengths
5195: 5168: 5150: 5099: 5071:
The circle is the shape with the largest area for a given length of perimeter (see
4450: 2185: 2112: 2077: 1804: 1800: 1759: 1625: 1617: 1496:: an extended chord, a coplanar straight line, intersecting a circle in two points. 1371: 1165: 1114: 927: 782: 697: 487: 48: 8769: 8218: 7655:{\displaystyle r={\frac {1}{\left|\sin \theta \right|+\left|\cos \theta \right|}}} 4027:
Without the ± sign, the equation would in some cases describe only half a circle.
8518: 8177: 8827: 7813: 7793: 7720: 6571: 6268: 5949: 5755: 5154: 5143: 1493: 1201: 1074: 892: 827: 755: 727: 702: 6240:
extended. Since the interior and exterior angles sum to 180 degrees, the angle
1774: 1537: 8743: 8091: 7537:
is 4 in this geometry. The formula for the unit circle in taxicab geometry is
7120: 7112: 6603: 5591:
is equal to one half the difference of the measurements of the enclosed arcs (
2116: 1930: 1633: 1527: 1499: 1365: 1059: 1038: 1028: 1018: 977: 922: 817: 807: 707: 558: 30:
This article is about the shape and mathematical concept. For other uses, see
8499: 8099: 1799:
and its derivatives (fish, eye, aureole, mandorla, etc.), the ouroboros, the
8759: 8754: 8619: 7967: 7081: 6021: 5766: 1645: 1345: 1333: 1317:. The distance between any point of the circle and the centre is called the 1069: 787: 750: 614: 586: 131: 8143: 8179:
The Six Books of Proclus, the Platonic Successor, on the Theology of Plato
2069:{\displaystyle \mathrm {Area} ={\frac {\pi d^{2}}{4}}\approx 0.7854d^{2},} 1687:
deals with the properties of circles. Euclid's definition of a circle is:
1586: 7845: 7840: 7727: 7681: 6515: 5928: 2463: 1725: 1403: 1349: 1322: 1150: 1109: 1079: 967: 962: 912: 637: 596: 544: 438: 401: 147: 6128:
satisfying the ratio of distances must fall on a particular circle. Let
1911: 17: 8173: 7091:
In 1882, the task was proven to be impossible, as a consequence of the
6622: 5779: 2981: 2166: 1721: 1505: 1084: 797: 591: 535: 335: 7730:, a circle is not limited to the geometric concept, but to all of its 6116:
The proof is in two parts. First, one must prove that, given two foci
2127:
measure 𝜃 of the angle is the ratio of the arc length to the radius:
1609: 8445: 7997: 7471: 7165: 6014:
Label the point of intersection of these two perpendicular bisectors
5142:
The circle that is centred at the origin with radius 1 is called the
2124: 1697: 1614: 1580: 1421: 1397: 1318: 1033: 1023: 902: 847: 722: 685: 673: 581: 499: 164: 8774:
for the properties of and elementary constructions involving circles
4704:{\displaystyle (x_{1}-a)x+(y_{1}-b)y=(x_{1}-a)x_{1}+(y_{1}-b)y_{1},} 1766:
in particular often used circles as an element of his compositions.
8610: 8327:
Richeson, David (2015). "Circular reasoning: who first proved that
6267:
A closely related property of circles involves the geometry of the
5338:
is the distance from the centre point to the point of intersection.
5191:
A perpendicular line from the centre of a circle bisects the chord.
1418:: the region common to (the intersection of) two overlapping discs. 1400:
of one circuit along the circle, or the distance around the circle.
8349: 7139: 6065: 5948: 5765: 5741: 5435: 2667: 2319: 2108: 1910: 1773: 1713: 1608: 1597: 1536: 1526: 1337: 1302: 1089: 1013: 947: 792: 396: 391: 6287:
for which the absolute value of the cross-ratio is equal to one:
6244:
is exactly 90 degrees; that is, a right angle. The set of points
6132:
be another point, also satisfying the ratio and lying on segment
5237:
An inscribed angle subtended by a diameter is a right angle (see
3807:
is the distance from the origin to the centre of the circle, and
3716:{\displaystyle r^{2}-2rr_{0}\cos(\theta -\phi )+r_{0}^{2}=a^{2},} 8739: 3761:
are the polar coordinates of a generic point on the circle, and
1341: 680: 530: 119: 4457:
on the circle is perpendicular to the diameter passing through
8547:. Mathworld.wolfram.com (2012-04-26). Retrieved on 2012-05-03. 8528:. Mathworld.wolfram.com (2012-04-26). Retrieved on 2012-05-03. 8509:. Mathworld.wolfram.com (2012-04-26). Retrieved on 2012-05-03. 3848:, or when the origin lies on the circle, the equation becomes 8785:
Click and drag points to see standard form equation in action
6882:
to the vertices of a given regular polygon with circumradius
4915:{\displaystyle {\frac {dy}{dx}}=-{\frac {x_{1}-a}{y_{1}-b}}.} 3800:
are the polar coordinates of the centre of the circle (i.e.,
7752: 1782:
in this 13th-century manuscript is a symbol of God's act of
7509:
is the circle's radius, its length in taxicab geometry is 2
4491:, then the tangent line is perpendicular to the line from ( 1672: 1336:
or a slice of round fruit. The circle is the basis for the
4317:{\displaystyle p=1,\ g=-{\overline {c}},\ q=r^{2}-|c|^{2}} 8594:"Cyclic Averages of Regular Polygons and Platonic Solids" 6733:. A circle is the special case of a supercircle in which 6476:{\displaystyle {\frac {|AP|}{|BP|}}={\frac {|AC|}{|BC|}}} 5056:{\displaystyle {\frac {dy}{dx}}=-{\frac {x_{1}}{y_{1}}}.} 2973:{\displaystyle (x_{1},y_{1}),(x_{2},y_{2}),(x_{3},y_{3})} 1830:
The ratio of a circle's circumference to its diameter is
8208:. History.mcs.st-andrews.ac.uk. Retrieved on 2012-05-03. 8130:. History.mcs.st-andrews.ac.uk. Retrieved on 2012-05-03. 6832:
are taken. The locus of points such that the sum of the
4568:, and the result is that the equation of the tangent is 5716:{\displaystyle 2\angle {CAB}=\angle {DOE}-\angle {BOC}} 5561:
If the angle subtended by the chord at the centre is 90
5126:
enclosed and the square of its radius are proportional.
4203:{\displaystyle pz{\overline {z}}+gz+{\overline {gz}}=q} 2850:
of the line passing through the centre parallel to the
2870:
The equation of the circle determined by three points
1578:), meaning "hoop" or "ring". The origins of the words 1384:: the point equidistant from all points on the circle. 7595: 7543: 7523: 7480: 7334: 7177: 7031: 6908: 6888: 6861: 6838: 6811: 6791: 6770: 6639: 6510:
Inscription in or circumscription about other figures
6389: 6293: 6157: 6109:, a line.) That circle is sometimes said to be drawn 5847:{\displaystyle r={\frac {y^{2}}{8x}}+{\frac {x}{2}}.} 5799: 5661: 5629: 5597: 4999: 4937: 4842: 4717: 4574: 4330: 4234: 4150: 4100: 4053: 3913: 3854: 3767: 3735: 3628: 3498: 2992: 2876: 2699: 2567: 2496: 2386: 2255: 2205: 2133: 2007: 1951: 1866: 1450: 1430: 1313:
that are at a given distance from a given point, the
8273:. Rizzoli International Publications, Incorporated. 8162:: A History of Man's Changing Vision of the Universe 5727:
is the centre of the circle (secant–secant theorem).
4814:{\displaystyle (x_{1}-a)(x-a)+(y_{1}-b)(y-b)=r^{2}.} 4228:. This becomes the above equation for a circle with 3903:
In the general case, the equation can be solved for
1444:
and required to be a positive number. A circle with
6548:that is tangent to each side of the polygon. Every 1755:cannot be performed with straightedge and compass. 130: 118: 104: 94: 41: 8693: 8660: 8422:"Introduction to the theory of analytic functions" 8295: 8189:Tr. Thomas Taylor (1816) Vol. 2, Ch. 2, "Of Plato" 7708:metrics does not generalize to higher dimensions. 7665:A circle of radius 1 (using this distance) is the 7654: 7581: 7529: 7493: 7452: 7316: 7044: 7017: 6894: 6874: 6847: 6824: 6797: 6776: 6703: 6475: 6343: 6228:extended bisects the corresponding exterior angle 6207:{\displaystyle {\frac {AP}{BP}}={\frac {AC}{BC}}.} 6206: 5846: 5715: 5647: 5615: 5055: 4985: 4914: 4813: 4703: 4423: 4316: 4202: 4134: 4084: 4019: 3893: 3792: 3753: 3715: 3576: 3469: 2972: 2828: 2646: 2538: 2452: 2290: 2223: 2155: 2068: 1987: 1896: 1803:, a rainbow, mandalas, rose windows and so forth. 1516:, that is, not containing their boundaries, or as 1512:All of the specified regions may be considered as 1462: 1436: 1364:: a ring-shaped object, the region bounded by two 8644:: CS1 maint: DOI inactive as of September 2024 ( 6694: 6665: 6498:are given distinct points in the plane, then the 6051:(it will also pass through the other two points). 5244:The diameter is the longest chord of the circle. 2980:not on a line is obtained by a conversion of the 1325:. A circle bounds a region of the plane called a 8302:(2nd ed.). Addison Wesley Longman. p.  7690:) on a plane is also a square with side length 2 7077:Squaring the circle is the problem, proposed by 2858:). However, this parameterisation works only if 2693:An alternative parametrisation of the circle is 1640:. Disc-shaped prehistoric artifacts include the 1522: 8383:, Dover, 2nd edition, 1996: pp. 104–105, #4–23. 6097:(other than 1) of distances to two fixed foci, 3577:{\displaystyle x^{2}+y^{2}-2axz-2byz+cz^{2}=0.} 1689: 8781:"Interactive Standard Form Equation of Circle" 8598:Communications in Mathematics and Applications 6602:approaches infinity. This fact was applied by 5958:Construction through three noncollinear points 2191:Using radians, the formula for the arc length 6330: 6296: 5451:The chord theorem states that if two chords, 3811:is the anticlockwise angle from the positive 2291:{\displaystyle A={\frac {1}{2}}\theta r^{2}.} 1278: 8: 6552:and every triangle is a tangential polygon. 1751:, proving that the millennia-old problem of 1531:Chord, secant, tangent, radius, and diameter 8538:Tangential Polygon – from Wolfram MathWorld 8397:29(4), September 1998, p. 331, problem 635. 8271:The Louvre Abu Dhabi: A World Vision of Art 7517:. Thus, the value of a geometric analog to 6805:points the vertices of the regular polygon 4094:In parametric form, this can be written as 3492:with the equation of a circle has the form 8298:A History of Mathematics / An Introduction 8245:"Why Did Wassily Kandinsky Paint Circles?" 6252:is a right angle forms a circle, of which 2453:{\displaystyle (x-a)^{2}+(y-b)^{2}=r^{2}.} 1988:{\displaystyle \mathrm {Area} =\pi r^{2}.} 1285: 1271: 1000: 519: 154: 143: 8609: 8348: 7602: 7594: 7568: 7560: 7552: 7544: 7542: 7522: 7481: 7479: 7439: 7429: 7405: 7395: 7377: 7367: 7356: 7347: 7333: 7301: 7297: 7286: 7276: 7252: 7242: 7224: 7214: 7190: 7176: 7036: 7030: 6971: 6958: 6939: 6934: 6924: 6913: 6907: 6887: 6866: 6860: 6837: 6816: 6810: 6790: 6769: 6688: 6674: 6659: 6645: 6638: 6465: 6454: 6447: 6436: 6433: 6422: 6411: 6404: 6393: 6390: 6388: 6329: 6328: 6295: 6294: 6292: 6181: 6158: 6156: 5831: 5812: 5806: 5798: 5702: 5685: 5668: 5660: 5630: 5628: 5598: 5596: 5293:and divides the other chord into lengths 5264:and divides the other chord into lengths 5042: 5032: 5026: 5000: 4998: 4974: 4958: 4942: 4936: 4894: 4876: 4869: 4843: 4841: 4802: 4765: 4725: 4716: 4692: 4673: 4657: 4638: 4610: 4582: 4573: 4411: 4395: 4376: 4363: 4351: 4346: 4331: 4329: 4308: 4303: 4294: 4285: 4259: 4233: 4179: 4157: 4149: 4114: 4099: 4068: 4054: 4052: 3988: 3978: 3973: 3960: 3954: 3924: 3912: 3853: 3775: 3766: 3734: 3704: 3691: 3686: 3652: 3633: 3627: 3562: 3516: 3503: 3497: 3452: 3439: 3423: 3410: 3391: 3378: 3362: 3349: 3331: 3318: 3302: 3289: 3270: 3257: 3241: 3228: 3218: 3203: 3189: 3177: 3163: 3148: 3134: 3122: 3108: 3094: 3080: 3068: 3054: 3039: 3025: 3013: 2999: 2993: 2991: 2961: 2948: 2929: 2916: 2897: 2884: 2875: 2810: 2789: 2754: 2736: 2723: 2700: 2698: 2627: 2591: 2568: 2566: 2527: 2514: 2501: 2495: 2441: 2428: 2403: 2385: 2279: 2262: 2254: 2204: 2199:and subtending an angle of measure 𝜃 is 2140: 2132: 2057: 2035: 2025: 2008: 2006: 1976: 1952: 1950: 1865: 1520:, including their respective boundaries. 1449: 1429: 1340:, which, with related inventions such as 7144:Illustrations of unit circles (see also 6020:. (They meet because the points are not 5648:{\displaystyle {\overset {\frown }{BC}}} 5616:{\displaystyle {\overset {\frown }{DE}}} 5232:is equal to the interior opposite angle. 5198:through the centre bisecting a chord is 3894:{\displaystyle r=2a\cos(\theta -\phi ).} 2846:can be interpreted geometrically as the 1786:. Notice also the circular shape of the 1671:(3.16049...) as an approximate value of 8043: 8019: 5098:). The group of rotations alone is the 5086:around the centre for every angle. Its 3606:: 0). These points are called the 2838:In this parameterisation, the ratio of 2156:{\displaystyle \theta ={\frac {s}{r}}.} 1732:, was connected to the divine for most 1239: 1173: 1122: 1051: 1003: 765: 627: 604: 571: 543: 146: 8637: 8060:, Henry George Liddell, Robert Scott, 5909:compass-and-straightedge constructions 5903:Compass and straightedge constructions 5129:The constants of proportionality are 2 5115:A circle circumference and radius are 1632:, and circular elements are common in 385:Straightedge and compass constructions 38: 8519:Circumcircle – from Wolfram MathWorld 7513:. Thus, a circle's circumference is 8 6598:sides has the circle as its limit as 6344:{\displaystyle {\bigl |}{\bigr |}=1.} 5529:and a secant from the external point 7: 8667:. Mineola, N.Y: Dover Publications. 7025:whose centre is the centroid of the 6559:is any convex polygon about which a 6483:is not a circle, but rather a line. 6383:satisfying the Apollonius condition 6124:and a ratio of distances, any point 6070:Apollonius' definition of a circle: 5770:The sagitta is the vertical segment. 4986:{\displaystyle x_{1}x+y_{1}y=r^{2},} 6271:of points in the complex plane. If 5758:(since the central angle is 180°). 3190: 3135: 3026: 3000: 2666:, interpreted geometrically as the 1997:Equivalently, denoting diameter by 8626:from the original on 22 April 2021 7831:Apollonius circle of the excircles 6151:, since the segments are similar: 6033:passing through one of the points 5699: 5682: 5665: 5319:equals the square of the diameter. 4144:The slightly generalised equation 2539:{\displaystyle x^{2}+y^{2}=r^{2}.} 2076:that is, approximately 79% of the 2018: 2015: 2012: 2009: 1962: 1959: 1956: 1953: 1945:multiplied by the radius squared: 27:Simple curve of Euclidean geometry 25: 8500:Incircle – from Wolfram MathWorld 8121:Chronology for 30000 BC to 500 BC 7915:of an orthodiagonal quadrilateral 6027:Construct the circle with centre 5939:Construct the circle with centre 5518:(corollary of the chord theorem). 4836:, then the slope of this line is 3164: 3109: 3081: 3055: 2983:3-point form of a circle equation 351:Noncommutative algebraic geometry 8696:Geometry: a comprehensive course 8381:Challenging Problems in Geometry 6379:, then the collection of points 5922:Construction with given diameter 5580:is the length of the chord, and 5368:intersect at the exterior point 2080:square (whose side is of length 1604:Santa Barbara County, California 47: 8359:10.4169/college.math.j.46.3.162 8337:The College Mathematics Journal 8003:Three points determine a circle 6970: 6617:is a set of points such that a 6375:is the midpoint of the segment 5899:, we find the required result. 5399:is a chord of the circle, then 5256:divides one chord into lengths 2856:Tangent half-angle substitution 2553:The equation can be written in 2111:, and that angle intercepts an 1897:{\displaystyle C=2\pi r=\pi d.} 1807:are part of some traditions of 8622:(inactive 11 September 2024). 8571:10.1080/00029890.2003.11919989 7569: 7561: 7553: 7545: 7343: 7337: 7186: 7180: 6582:The circle can be viewed as a 6578:Limiting case of other figures 6466: 6455: 6448: 6437: 6423: 6412: 6405: 6394: 6325: 6301: 5372:, then denoting the centre as 5254:intersection of any two chords 4792: 4780: 4777: 4758: 4752: 4740: 4737: 4718: 4685: 4666: 4650: 4631: 4622: 4603: 4594: 4575: 4347: 4332: 4304: 4295: 4069: 4055: 4009: 3997: 3948: 3936: 3885: 3873: 3787: 3768: 3748: 3736: 3676: 3664: 3622:, the equation of a circle is 3458: 3432: 3429: 3403: 3397: 3371: 3368: 3342: 3337: 3311: 3308: 3282: 3276: 3250: 3247: 3221: 3209: 3186: 3183: 3160: 3154: 3131: 3128: 3105: 3100: 3077: 3074: 3051: 3045: 3022: 3019: 2996: 2967: 2941: 2935: 2909: 2903: 2877: 2425: 2412: 2400: 2387: 744:- / other-dimensional 1: 8592:Meskhishvili, Mamuka (2020). 8559:American Mathematical Monthly 8243:Lesso, Rosie (15 June 2022). 7589:in Cartesian coordinates and 7093:Lindemann–Weierstrass theorem 4924:This can also be found using 3793:{\displaystyle (r_{0},\phi )} 3729:is the radius of the circle, 2233:and the formula for the area 1474:consisting of a single point. 7494:{\displaystyle {\sqrt {2}}r} 7171:, distance is determined by 6902:is constant is a circle, if 6633:has an equation of the form 6518:a unique circle, called the 6216:Analogously, a line segment 5584:is the radius of the circle. 5391:is tangent to the circle at 4416: 4400: 4381: 4368: 4264: 4189: 4162: 4135:{\displaystyle z=re^{it}+c.} 4039:, a circle with a centre at 2195:of a circular arc of radius 2165:The circular arc is said to 1915:Area enclosed by a circle = 8728:Encyclopedia of Mathematics 8490:, Dover, 2007 (orig. 1952). 8408:Advanced Euclidean Geometry 8394:College Mathematics Journal 7105:algebraic irrational number 6561:circle can be circumscribed 5860:and with sagitta of length 4479:and the circle has centre ( 3754:{\displaystyle (r,\theta )} 3608:circular points at infinity 2354:Cartesian coordinate system 2224:{\displaystyle s=\theta r,} 1919:× area of the shaded square 1770:Symbolism and religious use 1602:Circular cave paintings in 8844: 8770:"Interactive Java applets" 8659:Gamelin, Theodore (1999). 8486:Altshiller-Court, Nathan, 8223:Philadelphia Museum of Art 7070: 6586:of various other figures: 6364: 6059: 5789:of a chord and the length 5735: 5443: 5334:is the circle radius, and 5207:If a central angle and an 4564:) determines the value of 4442: 2686:) makes with the positive 2372:is the set of all points ( 1922: 1823: 29: 8379:Posamentier and Salkind, 8092:10.1017/S0003598X00049048 7907:Of certain quadrilaterals 7740:upon itself (known as an 7582:{\displaystyle |x|+|y|=1} 7470:= 1. Taxicab circles are 7328:= 2, giving the familiar 7107:; that is, it is not the 6764:Consider a finite set of 5555:(tangent–secant theorem). 5492:, also cut the circle at 2356:, the circle with centre 2336:) = (1.2, −0.5) 1939:area enclosed by a circle 1852:is related to the radius 1848:. Thus the circumference 46: 8663:Introduction to topology 8420:Harkness, James (1898). 8294:Katz, Victor J. (1998). 7988:Line–circle intersection 7789:Circle of antisimilitude 7769:Archimedes' twin circles 7667:von Neumann neighborhood 7095:, which proves that pi ( 7086:compass and straightedge 6538:tangential quadrilateral 5073:Isoperimetric inequality 4926:implicit differentiation 4445:Tangent lines to circles 4085:{\displaystyle |z-c|=r.} 3588:complex projective plane 2848:stereographic projection 2328: = 1, centre ( 2089:isoperimetric inequality 1624:Prehistoric people made 1541:Arc, sector, and segment 240:Non-Archimedean geometry 8620:10.26713/cma.v11i3.1420 8062:A Greek-English Lexicon 7886:Polar circle (geometry) 7748:Specially named circles 7324:In Euclidean geometry, 6855:-th power of distances 6752:curve of constant width 6546:circle can be inscribed 5746:Inscribed-angle theorem 5738:Inscribed angle theorem 3486:homogeneous coordinates 2559:trigonometric functions 1935:Measurement of a Circle 1741:Ferdinand von Lindemann 1730:astrology and astronomy 346:Noncommutative geometry 85: centre or origin 32:Circle (disambiguation) 8475:Excursions in Geometry 7876:Orthocentroidal circle 7712:Topological definition 7662:in polar coordinates. 7656: 7583: 7531: 7495: 7454: 7318: 7161: 7046: 7019: 6929: 6896: 6876: 6849: 6826: 6799: 6778: 6705: 6477: 6345: 6208: 6138:angle bisector theorem 6087: 6001:perpendicular bisector 5986:perpendicular bisector 5954: 5911:resulting in circles. 5848: 5771: 5747: 5717: 5649: 5617: 5441: 5186:perpendicular bisector 5057: 4987: 4916: 4815: 4705: 4513:), so it has the form 4425: 4318: 4224:is sometimes called a 4204: 4136: 4086: 4021: 3895: 3794: 3755: 3717: 3578: 3471: 2974: 2830: 2648: 2540: 2468:equation of the circle 2454: 2337: 2292: 2225: 2157: 2099:If a circle of radius 2070: 1989: 1920: 1898: 1791: 1710: 1644:and jade discs called 1621: 1606: 1542: 1532: 1464: 1438: 314:Discrete/Combinatorial 8792:"Munching on Circles" 8477:, Dover, 1969, 14–17. 8219:"Circles in a Circle" 7993:List of circle topics 7983:Inversion in a circle 7657: 7584: 7532: 7496: 7455: 7319: 7143: 7101:transcendental number 7047: 7045:{\displaystyle P_{n}} 7020: 6909: 6897: 6877: 6875:{\displaystyle d_{i}} 6850: 6827: 6825:{\displaystyle P_{n}} 6800: 6779: 6760:Locus of constant sum 6706: 6478: 6346: 6209: 6069: 6062:Circles of Apollonius 5952: 5849: 5769: 5745: 5718: 5650: 5618: 5440:Secant–secant theorem 5439: 5058: 4988: 4917: 4816: 4706: 4426: 4319: 4205: 4137: 4087: 4022: 3896: 3795: 3756: 3718: 3579: 3472: 2975: 2831: 2649: 2541: 2455: 2323: 2316:Cartesian coordinates 2293: 2226: 2158: 2071: 1990: 1914: 1899: 1777: 1612: 1601: 1590:are closely related. 1540: 1530: 1465: 1439: 297:Discrete differential 8410:, Dover Publ., 2007. 7978:Gauss circle problem 7593: 7541: 7530:{\displaystyle \pi } 7521: 7478: 7332: 7175: 7057:equilateral triangle 7029: 6906: 6886: 6859: 6836: 6809: 6789: 6768: 6723:. A supercircle has 6637: 6387: 6353:Stated another way, 6291: 6155: 6056:Circle of Apollonius 5797: 5659: 5627: 5595: 5533:meets the circle at 5525:meets the circle at 5226:cyclic quadrilateral 4997: 4935: 4840: 4715: 4572: 4328: 4232: 4148: 4098: 4051: 3911: 3852: 3765: 3733: 3626: 3496: 2990: 2874: 2697: 2565: 2494: 2384: 2341:Equation of a circle 2300:In the special case 2253: 2203: 2131: 2005: 1949: 1864: 1448: 1428: 58: circumference 8692:Pedoe, Dan (1988). 8438:1899Natur..59..386B 8406:Johnson, Roger A., 8199:Squaring the circle 8008:Translation of axes 7672:A circle of radius 7073:Squaring the circle 7067:Squaring the circle 7055:In the case of the 6947: 6361:Generalised circles 6220:through some point 6091:Apollonius of Perga 5778:(also known as the 5541:respectively, then 5500:respectively, then 5084:rotational symmetry 5080:reflection symmetry 3983: 3696: 2670:that the ray from ( 2662:in the range 0 to 2 2660:parametric variable 2561:sine and cosine as 2472:Pythagorean theorem 2470:, follows from the 1809:Western esotericism 1758:With the advent of 1753:squaring the circle 1463:{\displaystyle r=0} 564:Pythagorean theorem 8752:Weisstein, Eric W. 8543:2013-09-03 at the 8524:2012-01-20 at the 8505:2012-01-21 at the 8471:Ogilvy, C. Stanley 8460:on 7 October 2008. 8204:2008-06-24 at the 8185:2017-01-23 at the 8126:2008-03-22 at the 8056:2013-11-06 at the 7943:Villarceau circles 7920:Of a conic section 7913:Eight-point circle 7764:Archimedean circle 7759:Apollonian circles 7716:The circle is the 7678:Chebyshev distance 7652: 7579: 7527: 7491: 7450: 7314: 7162: 7042: 7015: 6930: 6892: 6872: 6848:{\displaystyle 2m} 6845: 6822: 6795: 6774: 6701: 6534:tangential polygon 6473: 6367:Generalised circle 6341: 6204: 6088: 5955: 5844: 5772: 5748: 5713: 5645: 5613: 5442: 5384:are supplementary. 5053: 4983: 4912: 4811: 4701: 4421: 4314: 4226:generalised circle 4200: 4132: 4082: 4017: 3969: 3891: 3825:, this reduces to 3790: 3751: 3713: 3682: 3574: 3467: 3194: 3168: 3139: 3113: 3085: 3059: 3030: 3004: 2970: 2826: 2824: 2644: 2642: 2536: 2450: 2338: 2288: 2221: 2153: 2103:is centred at the 2066: 1985: 1921: 1894: 1792: 1622: 1613:Circles in an old 1607: 1543: 1533: 1460: 1434: 1305:consisting of all 8818:Elementary shapes 8335:is a constant?". 8313:978-0-321-01618-8 7953: 7952: 7896:Van Lamoen circle 7871:Nine-point circle 7650: 7486: 7445: 7103:, rather than an 6978: 6974: 6973: where  6895:{\displaystyle R} 6798:{\displaystyle n} 6777:{\displaystyle n} 6682: 6653: 6565:bicentric polygon 6471: 6428: 6199: 6176: 6140:the line segment 5839: 5826: 5785:Given the length 5643: 5611: 5364:and a tangent at 5159:Riemannian circle 5157:, it becomes the 5048: 5018: 4993:and its slope is 4907: 4861: 4550:. Evaluating at ( 4419: 4403: 4384: 4371: 4274: 4267: 4249: 4192: 4165: 4047:has the equation 4012: 3620:polar coordinates 3614:Polar coordinates 3462: 3213: 2817: 2761: 2324:Circle of radius 2270: 2249:of measure 𝜃 is 2173:, which measures 2148: 2113:arc of the circle 2045: 1764:Wassily Kandinsky 1734:medieval scholars 1558:derives from the 1547: 1546: 1437:{\displaystyle r} 1295: 1294: 1260: 1259: 983:List of geometers 666:Three-dimensional 655: 654: 142: 141: 16:(Redirected from 8835: 8799: 8787: 8776: 8765: 8764: 8736: 8711: 8699: 8679: 8678: 8666: 8656: 8650: 8649: 8643: 8635: 8633: 8631: 8613: 8589: 8583: 8582: 8554: 8548: 8535: 8529: 8516: 8510: 8497: 8491: 8488:College Geometry 8484: 8478: 8468: 8462: 8461: 8456:. Archived from 8446:10.1038/059386a0 8417: 8411: 8404: 8398: 8390: 8384: 8377: 8371: 8370: 8352: 8330: 8324: 8318: 8317: 8301: 8291: 8285: 8284: 8266: 8260: 8259: 8257: 8255: 8240: 8234: 8233: 8231: 8229: 8215: 8209: 8196: 8190: 8171: 8165: 8160:The Sleepwalkers 8152: 8146: 8137: 8131: 8118: 8112: 8111: 8086:(336): 430–446. 8071: 8065: 8048: 8031: 8024: 7931:Directrix circle 7861:Malfatti circles 7784:Chromatic circle 7753: 7723:(the 1-sphere). 7661: 7659: 7658: 7653: 7651: 7649: 7648: 7644: 7626: 7622: 7603: 7588: 7586: 7585: 7580: 7572: 7564: 7556: 7548: 7536: 7534: 7533: 7528: 7503:Euclidean metric 7500: 7498: 7497: 7492: 7487: 7482: 7464:taxicab geometry 7459: 7457: 7456: 7451: 7446: 7444: 7443: 7438: 7434: 7433: 7410: 7409: 7404: 7400: 7399: 7382: 7381: 7376: 7372: 7371: 7357: 7352: 7351: 7346: 7323: 7321: 7320: 7315: 7310: 7309: 7305: 7296: 7292: 7291: 7290: 7285: 7281: 7280: 7257: 7256: 7251: 7247: 7246: 7229: 7228: 7223: 7219: 7218: 7195: 7194: 7189: 7159: 7153: 7098: 7061:regular pentagon 7051: 7049: 7048: 7043: 7041: 7040: 7024: 7022: 7021: 7016: 6976: 6975: 6972: 6966: 6965: 6946: 6938: 6928: 6923: 6901: 6899: 6898: 6893: 6881: 6879: 6878: 6873: 6871: 6870: 6854: 6852: 6851: 6846: 6831: 6829: 6828: 6823: 6821: 6820: 6804: 6802: 6801: 6796: 6783: 6781: 6780: 6775: 6739: 6732: 6710: 6708: 6707: 6702: 6693: 6692: 6687: 6683: 6675: 6664: 6663: 6658: 6654: 6646: 6592:regular polygons 6482: 6480: 6479: 6474: 6472: 6470: 6469: 6458: 6452: 6451: 6440: 6434: 6429: 6427: 6426: 6415: 6409: 6408: 6397: 6391: 6350: 6348: 6347: 6342: 6334: 6333: 6300: 6299: 6248:such that angle 6213: 6211: 6210: 6205: 6200: 6198: 6190: 6182: 6177: 6175: 6167: 6159: 6144:will bisect the 6085: 6050: 6044: 6038: 6032: 6019: 6010: 6009: 5995: 5994: 5980: 5974: 5968: 5963:Name the points 5944: 5936:of the diameter. 5935: 5894: 5874: 5853: 5851: 5850: 5845: 5840: 5832: 5827: 5825: 5817: 5816: 5807: 5732:Inscribed angles 5722: 5720: 5719: 5714: 5712: 5695: 5678: 5654: 5652: 5651: 5646: 5644: 5639: 5631: 5622: 5620: 5619: 5614: 5612: 5607: 5599: 5575: 5554: 5517: 5484:If two secants, 5480: 5446:Power of a point 5426: 5420: 5418: 5417: 5414: 5411: 5360:If a tangent at 5318: 5281: 5149:Thought of as a 5136: 5132: 5108:All circles are 5092:orthogonal group 5062: 5060: 5059: 5054: 5049: 5047: 5046: 5037: 5036: 5027: 5019: 5017: 5009: 5001: 4992: 4990: 4989: 4984: 4979: 4978: 4963: 4962: 4947: 4946: 4921: 4919: 4918: 4913: 4908: 4906: 4899: 4898: 4888: 4881: 4880: 4870: 4862: 4860: 4852: 4844: 4835: 4820: 4818: 4817: 4812: 4807: 4806: 4770: 4769: 4730: 4729: 4710: 4708: 4707: 4702: 4697: 4696: 4678: 4677: 4662: 4661: 4643: 4642: 4615: 4614: 4587: 4586: 4549: 4478: 4453:through a point 4430: 4428: 4427: 4422: 4420: 4412: 4404: 4396: 4385: 4377: 4372: 4364: 4356: 4355: 4350: 4335: 4323: 4321: 4320: 4315: 4313: 4312: 4307: 4298: 4290: 4289: 4272: 4268: 4260: 4247: 4209: 4207: 4206: 4201: 4193: 4188: 4180: 4166: 4158: 4141: 4139: 4138: 4133: 4122: 4121: 4091: 4089: 4088: 4083: 4072: 4058: 4026: 4024: 4023: 4018: 4013: 3993: 3992: 3982: 3977: 3965: 3964: 3955: 3929: 3928: 3900: 3898: 3897: 3892: 3847: 3834: 3824: 3799: 3797: 3796: 3791: 3780: 3779: 3760: 3758: 3757: 3752: 3722: 3720: 3719: 3714: 3709: 3708: 3695: 3690: 3657: 3656: 3638: 3637: 3583: 3581: 3580: 3575: 3567: 3566: 3521: 3520: 3508: 3507: 3480:Homogeneous form 3476: 3474: 3473: 3468: 3463: 3461: 3457: 3456: 3444: 3443: 3428: 3427: 3415: 3414: 3396: 3395: 3383: 3382: 3367: 3366: 3354: 3353: 3340: 3336: 3335: 3323: 3322: 3307: 3306: 3294: 3293: 3275: 3274: 3262: 3261: 3246: 3245: 3233: 3232: 3219: 3214: 3212: 3208: 3207: 3195: 3182: 3181: 3169: 3153: 3152: 3140: 3127: 3126: 3114: 3103: 3099: 3098: 3086: 3073: 3072: 3060: 3044: 3043: 3031: 3018: 3017: 3005: 2994: 2979: 2977: 2976: 2971: 2966: 2965: 2953: 2952: 2934: 2933: 2921: 2920: 2902: 2901: 2889: 2888: 2854: axis (see 2835: 2833: 2832: 2827: 2825: 2818: 2816: 2815: 2814: 2798: 2790: 2762: 2760: 2759: 2758: 2742: 2741: 2740: 2724: 2665: 2653: 2651: 2650: 2645: 2643: 2545: 2543: 2542: 2537: 2532: 2531: 2519: 2518: 2506: 2505: 2459: 2457: 2456: 2451: 2446: 2445: 2433: 2432: 2408: 2407: 2306: 2305: 2297: 2295: 2294: 2289: 2284: 2283: 2271: 2263: 2244: 2236: 2230: 2228: 2227: 2222: 2198: 2194: 2179: 2178: 2162: 2160: 2159: 2154: 2149: 2141: 2122: 2102: 2075: 2073: 2072: 2067: 2062: 2061: 2046: 2041: 2040: 2039: 2026: 2021: 1994: 1992: 1991: 1986: 1981: 1980: 1965: 1944: 1925:Area of a circle 1918: 1903: 1901: 1900: 1895: 1847: 1846: 1833: 1815:Analytic results 1746: 1708: 1675: 1670: 1668: 1667: 1664: 1661: 1523: 1469: 1467: 1466: 1461: 1443: 1441: 1440: 1435: 1287: 1280: 1273: 1001: 520: 453:Zero-dimensional 158: 144: 138: 126: 113: 84: 75: 66: 57: 51: 39: 21: 8843: 8842: 8838: 8837: 8836: 8834: 8833: 8832: 8803: 8802: 8790: 8779: 8768: 8750: 8749: 8721: 8718: 8708: 8691: 8688: 8686:Further reading 8683: 8682: 8675: 8658: 8657: 8653: 8636: 8629: 8627: 8591: 8590: 8586: 8556: 8555: 8551: 8545:Wayback Machine 8536: 8532: 8526:Wayback Machine 8517: 8513: 8507:Wayback Machine 8498: 8494: 8485: 8481: 8469: 8465: 8419: 8418: 8414: 8405: 8401: 8391: 8387: 8378: 8374: 8334: 8328: 8326: 8325: 8321: 8314: 8293: 8292: 8288: 8281: 8268: 8267: 8263: 8253: 8251: 8242: 8241: 8237: 8227: 8225: 8217: 8216: 8212: 8206:Wayback Machine 8197: 8193: 8187:Wayback Machine 8172: 8168: 8155:Arthur Koestler 8153: 8149: 8138: 8134: 8128:Wayback Machine 8119: 8115: 8073: 8072: 8068: 8058:Wayback Machine 8049: 8045: 8040: 8035: 8034: 8025: 8021: 8016: 7959: 7954: 7939: 7926:Director circle 7922: 7909: 7901: 7827: 7819: 7804:Johnson circles 7799:Geodesic circle 7750: 7742:ambient isotopy 7718:one-dimensional 7714: 7707: 7700: 7687: 7669:of its centre. 7634: 7630: 7612: 7608: 7607: 7591: 7590: 7539: 7538: 7519: 7518: 7476: 7475: 7425: 7421: 7420: 7391: 7387: 7386: 7363: 7359: 7358: 7336: 7335: 7330: 7329: 7272: 7268: 7267: 7238: 7234: 7233: 7210: 7206: 7205: 7204: 7200: 7199: 7179: 7178: 7173: 7172: 7155: 7149: 7148:) in different 7138: 7129: 7127:Generalizations 7096: 7075: 7069: 7032: 7027: 7026: 6954: 6904: 6903: 6884: 6883: 6862: 6857: 6856: 6834: 6833: 6812: 6807: 6806: 6787: 6786: 6766: 6765: 6762: 6734: 6724: 6670: 6669: 6641: 6640: 6635: 6634: 6580: 6550:regular polygon 6544:within which a 6512: 6453: 6435: 6410: 6392: 6385: 6384: 6369: 6363: 6289: 6288: 6265: 6256:is a diameter. 6191: 6183: 6168: 6160: 6153: 6152: 6084: 6077: 6071: 6064: 6058: 6046: 6040: 6034: 6028: 6015: 6005: 6004: 6003:of the segment 5990: 5989: 5988:of the segment 5976: 5970: 5964: 5960: 5940: 5931: 5924: 5907:There are many 5905: 5876: 5865: 5818: 5808: 5795: 5794: 5764: 5740: 5734: 5657: 5656: 5632: 5625: 5624: 5600: 5593: 5592: 5566: 5542: 5501: 5464: 5459:, intersect at 5448: 5434: 5415: 5412: 5409: 5408: 5406: 5400: 5348: 5302: 5273: 5239:Thales' theorem 5209:inscribed angle 5178: 5134: 5130: 5068: 5038: 5028: 5010: 5002: 4995: 4994: 4970: 4954: 4938: 4933: 4932: 4890: 4889: 4872: 4871: 4853: 4845: 4838: 4837: 4830: 4824: 4798: 4761: 4721: 4713: 4712: 4688: 4669: 4653: 4634: 4606: 4578: 4570: 4569: 4563: 4556: 4536: 4521: 4514: 4512: 4505: 4476: 4469: 4462: 4447: 4441: 4345: 4326: 4325: 4302: 4281: 4230: 4229: 4181: 4146: 4145: 4110: 4096: 4095: 4049: 4048: 4033: 3984: 3956: 3920: 3909: 3908: 3850: 3849: 3842: 3836: 3826: 3822: 3816: 3806: 3771: 3763: 3762: 3731: 3730: 3700: 3648: 3629: 3624: 3623: 3616: 3558: 3512: 3499: 3494: 3493: 3482: 3448: 3435: 3419: 3406: 3387: 3374: 3358: 3345: 3341: 3327: 3314: 3298: 3285: 3266: 3253: 3237: 3224: 3220: 3199: 3173: 3144: 3118: 3104: 3090: 3064: 3035: 3009: 2995: 2988: 2987: 2957: 2944: 2925: 2912: 2893: 2880: 2872: 2871: 2868: 2823: 2822: 2806: 2799: 2791: 2773: 2767: 2766: 2750: 2743: 2732: 2725: 2707: 2695: 2694: 2663: 2641: 2640: 2611: 2605: 2604: 2575: 2563: 2562: 2555:parametric form 2551: 2549:Parametric form 2523: 2510: 2497: 2492: 2491: 2466:, known as the 2437: 2424: 2399: 2382: 2381: 2343: 2318: 2313: 2303: 2301: 2275: 2251: 2250: 2242: 2239:circular sector 2234: 2201: 2200: 2196: 2192: 2176: 2174: 2129: 2128: 2120: 2100: 2097: 2053: 2031: 2027: 2003: 2002: 1972: 1947: 1946: 1942: 1927: 1916: 1909: 1862: 1861: 1844: 1842: 1831: 1828: 1822: 1817: 1772: 1744: 1724:, particularly 1709: 1696: 1673: 1665: 1662: 1659: 1658: 1656: 1596: 1562:κίρκος/κύκλος ( 1552: 1472:degenerate case 1446: 1445: 1426: 1425: 1358: 1291: 1262: 1261: 998: 997: 988: 987: 778: 777: 761: 760: 746: 745: 733: 732: 669: 668: 657: 656: 517: 516: 514:Two-dimensional 505: 504: 478: 477: 475:One-dimensional 466: 465: 456: 455: 444: 443: 377: 376: 375: 358: 357: 206: 205: 194: 171: 136: 124: 111: 90: 89: 82: 80: 73: 71: 67: diameter 64: 62: 55: 35: 28: 23: 22: 15: 12: 11: 5: 8841: 8839: 8831: 8830: 8825: 8823:Conic sections 8820: 8815: 8805: 8804: 8801: 8800: 8788: 8777: 8766: 8747: 8737: 8717: 8716:External links 8714: 8713: 8712: 8706: 8687: 8684: 8681: 8680: 8673: 8651: 8584: 8565:(6): 516–526. 8549: 8530: 8511: 8492: 8479: 8463: 8412: 8399: 8385: 8372: 8343:(3): 162–171. 8332: 8319: 8312: 8286: 8279: 8261: 8235: 8210: 8191: 8166: 8147: 8132: 8113: 8066: 8042: 8041: 8039: 8036: 8033: 8032: 8026:Also known as 8018: 8017: 8015: 8012: 8011: 8010: 8005: 8000: 7995: 7990: 7985: 7980: 7975: 7973:Circle fitting 7970: 7965: 7958: 7955: 7951: 7950: 7946: 7945: 7938: 7935: 7934: 7933: 7928: 7921: 7918: 7917: 7916: 7908: 7905: 7903: 7899: 7898: 7893: 7891:Spieker circle 7888: 7883: 7878: 7873: 7868: 7866:Mandart circle 7863: 7858: 7853: 7851:Lemoine circle 7848: 7843: 7838: 7836:Brocard circle 7833: 7826: 7823: 7821: 7817: 7816: 7811: 7809:Schoch circles 7806: 7801: 7796: 7791: 7786: 7781: 7779:Carlyle circle 7776: 7774:Bankoff circle 7771: 7766: 7761: 7751: 7749: 7746: 7732:homeomorphisms 7713: 7710: 7705: 7698: 7685: 7647: 7643: 7640: 7637: 7633: 7629: 7625: 7621: 7618: 7615: 7611: 7606: 7601: 7598: 7578: 7575: 7571: 7567: 7563: 7559: 7555: 7551: 7547: 7526: 7490: 7485: 7449: 7442: 7437: 7432: 7428: 7424: 7419: 7416: 7413: 7408: 7403: 7398: 7394: 7390: 7385: 7380: 7375: 7370: 7366: 7362: 7355: 7350: 7345: 7342: 7339: 7313: 7308: 7304: 7300: 7295: 7289: 7284: 7279: 7275: 7271: 7266: 7263: 7260: 7255: 7250: 7245: 7241: 7237: 7232: 7227: 7222: 7217: 7213: 7209: 7203: 7198: 7193: 7188: 7185: 7182: 7137: 7130: 7128: 7125: 7071:Main article: 7068: 7065: 7039: 7035: 7014: 7011: 7008: 7005: 7002: 6999: 6996: 6993: 6990: 6987: 6984: 6981: 6969: 6964: 6961: 6957: 6953: 6950: 6945: 6942: 6937: 6933: 6927: 6922: 6919: 6916: 6912: 6891: 6869: 6865: 6844: 6841: 6819: 6815: 6794: 6773: 6761: 6758: 6757: 6756: 6748: 6741: 6700: 6697: 6691: 6686: 6681: 6678: 6673: 6668: 6662: 6657: 6652: 6649: 6644: 6627: 6615:Cartesian oval 6611: 6590:The series of 6579: 6576: 6557:cyclic polygon 6542:convex polygon 6511: 6508: 6468: 6464: 6461: 6457: 6450: 6446: 6443: 6439: 6432: 6425: 6421: 6418: 6414: 6407: 6403: 6400: 6396: 6362: 6359: 6340: 6337: 6332: 6327: 6324: 6321: 6318: 6315: 6312: 6309: 6306: 6303: 6298: 6264: 6261: 6203: 6197: 6194: 6189: 6186: 6180: 6174: 6171: 6166: 6163: 6146:interior angle 6082: 6075: 6057: 6054: 6053: 6052: 6025: 6012: 5999:Construct the 5997: 5984:Construct the 5982: 5959: 5956: 5947: 5946: 5937: 5927:Construct the 5923: 5920: 5904: 5901: 5895:. Solving for 5843: 5838: 5835: 5830: 5824: 5821: 5815: 5811: 5805: 5802: 5763: 5760: 5733: 5730: 5729: 5728: 5711: 5708: 5705: 5701: 5698: 5694: 5691: 5688: 5684: 5681: 5677: 5674: 5671: 5667: 5664: 5642: 5638: 5635: 5610: 5606: 5603: 5585: 5559: 5556: 5519: 5482: 5433: 5430: 5429: 5428: 5385: 5376:, the angles ∠ 5358: 5355: 5352: 5347: 5344: 5343: 5342: 5339: 5320: 5283: 5250: 5249: 5248: 5242: 5235: 5234: 5233: 5230:exterior angle 5215: 5212: 5205: 5204: 5203: 5192: 5182: 5177: 5174: 5173: 5172: 5164: 5163: 5162: 5140: 5139: 5138: 5127: 5120: 5106: 5088:symmetry group 5076: 5067: 5064: 5052: 5045: 5041: 5035: 5031: 5025: 5022: 5016: 5013: 5008: 5005: 4982: 4977: 4973: 4969: 4966: 4961: 4957: 4953: 4950: 4945: 4941: 4911: 4905: 4902: 4897: 4893: 4887: 4884: 4879: 4875: 4868: 4865: 4859: 4856: 4851: 4848: 4828: 4810: 4805: 4801: 4797: 4794: 4791: 4788: 4785: 4782: 4779: 4776: 4773: 4768: 4764: 4760: 4757: 4754: 4751: 4748: 4745: 4742: 4739: 4736: 4733: 4728: 4724: 4720: 4700: 4695: 4691: 4687: 4684: 4681: 4676: 4672: 4668: 4665: 4660: 4656: 4652: 4649: 4646: 4641: 4637: 4633: 4630: 4627: 4624: 4621: 4618: 4613: 4609: 4605: 4602: 4599: 4596: 4593: 4590: 4585: 4581: 4577: 4561: 4554: 4534: 4519: 4510: 4503: 4474: 4467: 4443:Main article: 4440: 4437: 4418: 4415: 4410: 4407: 4402: 4399: 4394: 4391: 4388: 4383: 4380: 4375: 4370: 4367: 4362: 4359: 4354: 4349: 4344: 4341: 4338: 4334: 4311: 4306: 4301: 4297: 4293: 4288: 4284: 4280: 4277: 4271: 4266: 4263: 4258: 4255: 4252: 4246: 4243: 4240: 4237: 4199: 4196: 4191: 4187: 4184: 4178: 4175: 4172: 4169: 4164: 4161: 4156: 4153: 4131: 4128: 4125: 4120: 4117: 4113: 4109: 4106: 4103: 4081: 4078: 4075: 4071: 4067: 4064: 4061: 4057: 4032: 4029: 4016: 4011: 4008: 4005: 4002: 3999: 3996: 3991: 3987: 3981: 3976: 3972: 3968: 3963: 3959: 3953: 3950: 3947: 3944: 3941: 3938: 3935: 3932: 3927: 3923: 3919: 3916: 3890: 3887: 3884: 3881: 3878: 3875: 3872: 3869: 3866: 3863: 3860: 3857: 3840: 3820: 3804: 3789: 3786: 3783: 3778: 3774: 3770: 3750: 3747: 3744: 3741: 3738: 3712: 3707: 3703: 3699: 3694: 3689: 3685: 3681: 3678: 3675: 3672: 3669: 3666: 3663: 3660: 3655: 3651: 3647: 3644: 3641: 3636: 3632: 3615: 3612: 3573: 3570: 3565: 3561: 3557: 3554: 3551: 3548: 3545: 3542: 3539: 3536: 3533: 3530: 3527: 3524: 3519: 3515: 3511: 3506: 3502: 3481: 3478: 3466: 3460: 3455: 3451: 3447: 3442: 3438: 3434: 3431: 3426: 3422: 3418: 3413: 3409: 3405: 3402: 3399: 3394: 3390: 3386: 3381: 3377: 3373: 3370: 3365: 3361: 3357: 3352: 3348: 3344: 3339: 3334: 3330: 3326: 3321: 3317: 3313: 3310: 3305: 3301: 3297: 3292: 3288: 3284: 3281: 3278: 3273: 3269: 3265: 3260: 3256: 3252: 3249: 3244: 3240: 3236: 3231: 3227: 3223: 3217: 3211: 3206: 3202: 3198: 3193: 3188: 3185: 3180: 3176: 3172: 3167: 3162: 3159: 3156: 3151: 3147: 3143: 3138: 3133: 3130: 3125: 3121: 3117: 3112: 3107: 3102: 3097: 3093: 3089: 3084: 3079: 3076: 3071: 3067: 3063: 3058: 3053: 3050: 3047: 3042: 3038: 3034: 3029: 3024: 3021: 3016: 3012: 3008: 3003: 2998: 2969: 2964: 2960: 2956: 2951: 2947: 2943: 2940: 2937: 2932: 2928: 2924: 2919: 2915: 2911: 2908: 2905: 2900: 2896: 2892: 2887: 2883: 2879: 2867: 2864: 2821: 2813: 2809: 2805: 2802: 2797: 2794: 2788: 2785: 2782: 2779: 2776: 2774: 2772: 2769: 2768: 2765: 2757: 2753: 2749: 2746: 2739: 2735: 2731: 2728: 2722: 2719: 2716: 2713: 2710: 2708: 2706: 2703: 2702: 2639: 2636: 2633: 2630: 2626: 2623: 2620: 2617: 2614: 2612: 2610: 2607: 2606: 2603: 2600: 2597: 2594: 2590: 2587: 2584: 2581: 2578: 2576: 2574: 2571: 2570: 2550: 2547: 2535: 2530: 2526: 2522: 2517: 2513: 2509: 2504: 2500: 2449: 2444: 2440: 2436: 2431: 2427: 2423: 2420: 2417: 2414: 2411: 2406: 2402: 2398: 2395: 2392: 2389: 2342: 2339: 2317: 2314: 2312: 2309: 2287: 2282: 2278: 2274: 2269: 2266: 2261: 2258: 2220: 2217: 2214: 2211: 2208: 2171:complete angle 2152: 2147: 2144: 2139: 2136: 2096: 2093: 2078:circumscribing 2065: 2060: 2056: 2052: 2049: 2044: 2038: 2034: 2030: 2024: 2020: 2017: 2014: 2011: 1984: 1979: 1975: 1971: 1968: 1964: 1961: 1958: 1955: 1923:Main article: 1908: 1905: 1893: 1890: 1887: 1884: 1881: 1878: 1875: 1872: 1869: 1824:Main article: 1821: 1818: 1816: 1813: 1771: 1768: 1749:transcendental 1718:Seventh Letter 1694: 1642:Nebra sky disc 1638:cave paintings 1630:timber circles 1595: 1592: 1551: 1548: 1545: 1544: 1534: 1510: 1509: 1503: 1497: 1491: 1481: 1475: 1459: 1456: 1453: 1433: 1419: 1413: 1407: 1401: 1391: 1385: 1379: 1369: 1357: 1354: 1293: 1292: 1290: 1289: 1282: 1275: 1267: 1264: 1263: 1258: 1257: 1256: 1255: 1250: 1242: 1241: 1237: 1236: 1235: 1234: 1229: 1224: 1219: 1214: 1209: 1204: 1199: 1194: 1189: 1184: 1176: 1175: 1171: 1170: 1169: 1168: 1163: 1158: 1153: 1148: 1143: 1138: 1133: 1125: 1124: 1120: 1119: 1118: 1117: 1112: 1107: 1102: 1097: 1092: 1087: 1082: 1077: 1072: 1067: 1062: 1054: 1053: 1049: 1048: 1047: 1046: 1041: 1036: 1031: 1026: 1021: 1016: 1008: 1007: 999: 995: 994: 993: 990: 989: 986: 985: 980: 975: 970: 965: 960: 955: 950: 945: 940: 935: 930: 925: 920: 915: 910: 905: 900: 895: 890: 885: 880: 875: 870: 865: 860: 855: 850: 845: 840: 835: 830: 825: 820: 815: 810: 805: 800: 795: 790: 785: 779: 775: 774: 773: 770: 769: 763: 762: 759: 758: 753: 747: 740: 739: 738: 735: 734: 731: 730: 725: 720: 718:Platonic Solid 715: 710: 705: 700: 695: 690: 689: 688: 677: 676: 670: 664: 663: 662: 659: 658: 653: 652: 651: 650: 645: 640: 632: 631: 625: 624: 623: 622: 617: 609: 608: 602: 601: 600: 599: 594: 589: 584: 576: 575: 569: 568: 567: 566: 561: 556: 548: 547: 541: 540: 539: 538: 533: 528: 518: 512: 511: 510: 507: 506: 503: 502: 497: 496: 495: 490: 479: 473: 472: 471: 468: 467: 464: 463: 457: 451: 450: 449: 446: 445: 442: 441: 436: 431: 425: 424: 419: 414: 404: 399: 394: 388: 387: 378: 374: 373: 370: 366: 365: 364: 363: 360: 359: 356: 355: 354: 353: 343: 338: 333: 328: 323: 322: 321: 311: 306: 301: 300: 299: 294: 289: 279: 278: 277: 272: 262: 257: 252: 247: 242: 237: 236: 235: 230: 229: 228: 213: 207: 201: 200: 199: 196: 195: 193: 192: 182: 176: 173: 172: 159: 151: 150: 140: 139: 134: 128: 127: 122: 116: 115: 108: 106:Symmetry group 102: 101: 96: 92: 91: 81: 72: 63: 54: 52: 44: 43: 26: 24: 14: 13: 10: 9: 6: 4: 3: 2: 8840: 8829: 8826: 8824: 8821: 8819: 8816: 8814: 8811: 8810: 8808: 8797: 8793: 8789: 8786: 8782: 8778: 8775: 8771: 8767: 8762: 8761: 8756: 8753: 8748: 8745: 8741: 8738: 8734: 8730: 8729: 8724: 8720: 8719: 8715: 8709: 8707:9780486658124 8703: 8698: 8697: 8690: 8689: 8685: 8676: 8670: 8665: 8664: 8655: 8652: 8647: 8641: 8625: 8621: 8617: 8612: 8607: 8603: 8599: 8595: 8588: 8585: 8580: 8576: 8572: 8568: 8564: 8560: 8553: 8550: 8546: 8542: 8539: 8534: 8531: 8527: 8523: 8520: 8515: 8512: 8508: 8504: 8501: 8496: 8493: 8489: 8483: 8480: 8476: 8472: 8467: 8464: 8459: 8455: 8451: 8447: 8443: 8439: 8435: 8431: 8427: 8423: 8416: 8413: 8409: 8403: 8400: 8396: 8395: 8389: 8386: 8382: 8376: 8373: 8368: 8364: 8360: 8356: 8351: 8346: 8342: 8338: 8323: 8320: 8315: 8309: 8305: 8300: 8299: 8290: 8287: 8282: 8280:9782370741004 8276: 8272: 8265: 8262: 8250: 8246: 8239: 8236: 8224: 8220: 8214: 8211: 8207: 8203: 8200: 8195: 8192: 8188: 8184: 8181: 8180: 8175: 8170: 8167: 8163: 8161: 8156: 8151: 8148: 8145: 8141: 8136: 8133: 8129: 8125: 8122: 8117: 8114: 8109: 8105: 8101: 8097: 8093: 8089: 8085: 8081: 8077: 8070: 8067: 8063: 8059: 8055: 8052: 8047: 8044: 8037: 8029: 8023: 8020: 8013: 8009: 8006: 8004: 8001: 7999: 7996: 7994: 7991: 7989: 7986: 7984: 7981: 7979: 7976: 7974: 7971: 7969: 7966: 7964: 7963:Affine sphere 7961: 7960: 7956: 7949: 7944: 7941: 7940: 7936: 7932: 7929: 7927: 7924: 7923: 7919: 7914: 7911: 7910: 7906: 7904: 7902: 7897: 7894: 7892: 7889: 7887: 7884: 7882: 7879: 7877: 7874: 7872: 7869: 7867: 7864: 7862: 7859: 7857: 7856:Lester circle 7854: 7852: 7849: 7847: 7844: 7842: 7839: 7837: 7834: 7832: 7829: 7828: 7825:Of a triangle 7824: 7822: 7820: 7815: 7812: 7810: 7807: 7805: 7802: 7800: 7797: 7795: 7792: 7790: 7787: 7785: 7782: 7780: 7777: 7775: 7772: 7770: 7767: 7765: 7762: 7760: 7757: 7756: 7755: 7754: 7747: 7745: 7743: 7739: 7738: 7733: 7729: 7724: 7722: 7719: 7711: 7709: 7704: 7697: 7693: 7689: 7684: 7679: 7675: 7670: 7668: 7663: 7645: 7641: 7638: 7635: 7631: 7627: 7623: 7619: 7616: 7613: 7609: 7604: 7599: 7596: 7576: 7573: 7565: 7557: 7549: 7524: 7516: 7512: 7508: 7504: 7488: 7483: 7473: 7469: 7465: 7460: 7447: 7440: 7435: 7430: 7426: 7422: 7417: 7414: 7411: 7406: 7401: 7396: 7392: 7388: 7383: 7378: 7373: 7368: 7364: 7360: 7353: 7348: 7340: 7327: 7311: 7306: 7302: 7298: 7293: 7287: 7282: 7277: 7273: 7269: 7264: 7261: 7258: 7253: 7248: 7243: 7239: 7235: 7230: 7225: 7220: 7215: 7211: 7207: 7201: 7196: 7191: 7183: 7170: 7168: 7158: 7152: 7147: 7142: 7135: 7131: 7126: 7124: 7123:enthusiasts. 7122: 7118: 7114: 7110: 7106: 7102: 7094: 7089: 7087: 7083: 7080: 7074: 7066: 7064: 7062: 7058: 7053: 7037: 7033: 7012: 7009: 7006: 7003: 7000: 6997: 6994: 6991: 6988: 6985: 6982: 6979: 6967: 6962: 6959: 6955: 6951: 6948: 6943: 6940: 6935: 6931: 6925: 6920: 6917: 6914: 6910: 6889: 6867: 6863: 6842: 6839: 6817: 6813: 6792: 6771: 6759: 6753: 6749: 6746: 6742: 6737: 6731: 6727: 6722: 6718: 6714: 6711:for positive 6698: 6695: 6689: 6684: 6679: 6676: 6671: 6666: 6660: 6655: 6650: 6647: 6642: 6632: 6628: 6624: 6620: 6616: 6612: 6609: 6608:approximate π 6605: 6601: 6597: 6593: 6589: 6588: 6587: 6585: 6584:limiting case 6577: 6575: 6573: 6568: 6566: 6562: 6558: 6553: 6551: 6547: 6543: 6539: 6535: 6530: 6528: 6523: 6521: 6517: 6509: 6507: 6505: 6501: 6497: 6493: 6489: 6484: 6462: 6459: 6444: 6441: 6430: 6419: 6416: 6401: 6398: 6382: 6378: 6374: 6368: 6360: 6358: 6356: 6351: 6338: 6335: 6322: 6319: 6316: 6313: 6310: 6307: 6304: 6286: 6282: 6278: 6274: 6270: 6262: 6260: 6257: 6255: 6251: 6247: 6243: 6239: 6235: 6231: 6227: 6223: 6219: 6214: 6201: 6195: 6192: 6187: 6184: 6178: 6172: 6169: 6164: 6161: 6150: 6147: 6143: 6139: 6135: 6131: 6127: 6123: 6119: 6114: 6112: 6108: 6104: 6100: 6096: 6092: 6081: 6074: 6068: 6063: 6055: 6049: 6043: 6037: 6031: 6026: 6023: 6018: 6013: 6008: 6002: 5998: 5993: 5987: 5983: 5979: 5973: 5967: 5962: 5961: 5957: 5951: 5943: 5938: 5934: 5930: 5926: 5925: 5921: 5919: 5917: 5912: 5910: 5902: 5900: 5898: 5892: 5888: 5884: 5880: 5873: 5869: 5863: 5859: 5854: 5841: 5836: 5833: 5828: 5822: 5819: 5813: 5809: 5803: 5800: 5792: 5788: 5783: 5781: 5777: 5768: 5761: 5759: 5757: 5753: 5752:central angle 5744: 5739: 5731: 5726: 5709: 5706: 5703: 5696: 5692: 5689: 5686: 5679: 5675: 5672: 5669: 5662: 5640: 5636: 5633: 5608: 5604: 5601: 5590: 5586: 5583: 5579: 5573: 5569: 5564: 5560: 5557: 5553: 5549: 5545: 5540: 5536: 5532: 5528: 5524: 5520: 5516: 5512: 5508: 5504: 5499: 5495: 5491: 5487: 5483: 5479: 5475: 5471: 5467: 5462: 5458: 5454: 5450: 5449: 5447: 5438: 5431: 5424: 5404: 5398: 5394: 5390: 5386: 5383: 5379: 5375: 5371: 5367: 5363: 5359: 5356: 5353: 5350: 5349: 5345: 5340: 5337: 5333: 5329: 5325: 5321: 5317: 5313: 5309: 5305: 5300: 5296: 5292: 5288: 5284: 5280: 5276: 5271: 5267: 5263: 5259: 5255: 5251: 5246: 5245: 5243: 5240: 5236: 5231: 5227: 5223: 5222: 5220: 5219:supplementary 5216: 5213: 5210: 5206: 5202:to the chord. 5201: 5200:perpendicular 5197: 5193: 5190: 5189: 5187: 5183: 5180: 5179: 5175: 5170: 5165: 5160: 5156: 5152: 5148: 5147: 5145: 5141: 5137:respectively. 5128: 5125: 5121: 5118: 5114: 5113: 5111: 5107: 5104: 5101: 5097: 5093: 5089: 5085: 5082:, and it has 5081: 5077: 5074: 5070: 5069: 5065: 5063: 5050: 5043: 5039: 5033: 5029: 5023: 5020: 5014: 5011: 5006: 5003: 4980: 4975: 4971: 4967: 4964: 4959: 4955: 4951: 4948: 4943: 4939: 4929: 4927: 4922: 4909: 4903: 4900: 4895: 4891: 4885: 4882: 4877: 4873: 4866: 4863: 4857: 4854: 4849: 4846: 4834: 4827: 4821: 4808: 4803: 4799: 4795: 4789: 4786: 4783: 4774: 4771: 4766: 4762: 4755: 4749: 4746: 4743: 4734: 4731: 4726: 4722: 4698: 4693: 4689: 4682: 4679: 4674: 4670: 4663: 4658: 4654: 4647: 4644: 4639: 4635: 4628: 4625: 4619: 4616: 4611: 4607: 4600: 4597: 4591: 4588: 4583: 4579: 4567: 4560: 4553: 4548: 4544: 4540: 4533: 4529: 4525: 4518: 4509: 4502: 4498: 4494: 4490: 4487:) and radius 4486: 4482: 4473: 4466: 4460: 4456: 4452: 4446: 4439:Tangent lines 4438: 4436: 4434: 4413: 4408: 4405: 4397: 4392: 4389: 4386: 4378: 4373: 4365: 4360: 4357: 4352: 4342: 4339: 4336: 4309: 4299: 4291: 4286: 4282: 4278: 4275: 4269: 4261: 4256: 4253: 4250: 4244: 4241: 4238: 4235: 4227: 4223: 4219: 4215: 4210: 4197: 4194: 4185: 4182: 4176: 4173: 4170: 4167: 4159: 4154: 4151: 4142: 4129: 4126: 4123: 4118: 4115: 4111: 4107: 4104: 4101: 4092: 4079: 4076: 4073: 4065: 4062: 4059: 4046: 4042: 4038: 4037:complex plane 4031:Complex plane 4030: 4028: 4014: 4006: 4003: 4000: 3994: 3989: 3985: 3979: 3974: 3970: 3966: 3961: 3957: 3951: 3945: 3942: 3939: 3933: 3930: 3925: 3921: 3917: 3914: 3906: 3901: 3888: 3882: 3879: 3876: 3870: 3867: 3864: 3861: 3858: 3855: 3846: 3839: 3833: 3829: 3819: 3814: 3810: 3803: 3784: 3781: 3776: 3772: 3745: 3742: 3739: 3728: 3723: 3710: 3705: 3701: 3697: 3692: 3687: 3683: 3679: 3673: 3670: 3667: 3661: 3658: 3653: 3649: 3645: 3642: 3639: 3634: 3630: 3621: 3613: 3611: 3609: 3605: 3601: 3597: 3593: 3590:) the points 3589: 3584: 3571: 3568: 3563: 3559: 3555: 3552: 3549: 3546: 3543: 3540: 3537: 3534: 3531: 3528: 3525: 3522: 3517: 3513: 3509: 3504: 3500: 3491: 3490:conic section 3487: 3479: 3477: 3464: 3453: 3449: 3445: 3440: 3436: 3424: 3420: 3416: 3411: 3407: 3400: 3392: 3388: 3384: 3379: 3375: 3363: 3359: 3355: 3350: 3346: 3332: 3328: 3324: 3319: 3315: 3303: 3299: 3295: 3290: 3286: 3279: 3271: 3267: 3263: 3258: 3254: 3242: 3238: 3234: 3229: 3225: 3215: 3204: 3200: 3196: 3191: 3178: 3174: 3170: 3165: 3157: 3149: 3145: 3141: 3136: 3123: 3119: 3115: 3110: 3095: 3091: 3087: 3082: 3069: 3065: 3061: 3056: 3048: 3040: 3036: 3032: 3027: 3014: 3010: 3006: 3001: 2985: 2984: 2962: 2958: 2954: 2949: 2945: 2938: 2930: 2926: 2922: 2917: 2913: 2906: 2898: 2894: 2890: 2885: 2881: 2865: 2863: 2861: 2857: 2853: 2849: 2845: 2841: 2836: 2819: 2811: 2807: 2803: 2800: 2795: 2792: 2786: 2783: 2780: 2777: 2775: 2770: 2763: 2755: 2751: 2747: 2744: 2737: 2733: 2729: 2726: 2720: 2717: 2714: 2711: 2709: 2704: 2691: 2689: 2685: 2681: 2677: 2673: 2669: 2661: 2657: 2637: 2634: 2631: 2628: 2624: 2621: 2618: 2615: 2613: 2608: 2601: 2598: 2595: 2592: 2588: 2585: 2582: 2579: 2577: 2572: 2560: 2556: 2548: 2546: 2533: 2528: 2524: 2520: 2515: 2511: 2507: 2502: 2498: 2489: 2485: 2481: 2477: 2473: 2469: 2465: 2460: 2447: 2442: 2438: 2434: 2429: 2421: 2418: 2415: 2409: 2404: 2396: 2393: 2390: 2379: 2375: 2371: 2368:) and radius 2367: 2363: 2359: 2355: 2352: 2348: 2340: 2335: 2331: 2327: 2322: 2315: 2310: 2308: 2298: 2285: 2280: 2276: 2272: 2267: 2264: 2259: 2256: 2248: 2247:central angle 2240: 2231: 2218: 2215: 2212: 2209: 2206: 2189: 2187: 2183: 2180:radians, 360 2172: 2168: 2163: 2150: 2145: 2142: 2137: 2134: 2126: 2118: 2114: 2110: 2106: 2094: 2092: 2090: 2085: 2083: 2079: 2063: 2058: 2054: 2050: 2047: 2042: 2036: 2032: 2028: 2022: 2000: 1995: 1982: 1977: 1973: 1969: 1966: 1940: 1936: 1932: 1929:As proved by 1926: 1913: 1907:Area enclosed 1906: 1904: 1891: 1888: 1885: 1882: 1879: 1876: 1873: 1870: 1867: 1859: 1856:and diameter 1855: 1851: 1840: 1837: 1827: 1826:Circumference 1820:Circumference 1819: 1814: 1812: 1810: 1806: 1805:Magic circles 1802: 1796: 1789: 1785: 1781: 1776: 1769: 1767: 1765: 1761: 1756: 1754: 1750: 1742: 1737: 1735: 1731: 1727: 1723: 1719: 1715: 1707: 1703: 1699: 1693: 1688: 1686: 1685: 1678: 1676: 1654: 1653:Rhind papyrus 1651:The Egyptian 1649: 1647: 1643: 1639: 1635: 1631: 1627: 1626:stone circles 1619: 1616: 1611: 1605: 1600: 1593: 1591: 1589: 1588: 1583: 1582: 1577: 1573: 1572:Homeric Greek 1569: 1565: 1564:kirkos/kuklos 1561: 1557: 1549: 1539: 1535: 1529: 1525: 1524: 1521: 1519: 1515: 1507: 1504: 1501: 1498: 1495: 1492: 1489: 1485: 1482: 1479: 1476: 1473: 1457: 1454: 1451: 1431: 1423: 1420: 1417: 1414: 1411: 1408: 1405: 1402: 1399: 1395: 1394:Circumference 1392: 1389: 1386: 1383: 1380: 1377: 1373: 1370: 1367: 1363: 1360: 1359: 1355: 1353: 1351: 1347: 1343: 1339: 1335: 1330: 1328: 1324: 1320: 1316: 1312: 1308: 1304: 1300: 1288: 1283: 1281: 1276: 1274: 1269: 1268: 1266: 1265: 1254: 1251: 1249: 1246: 1245: 1244: 1243: 1238: 1233: 1230: 1228: 1225: 1223: 1220: 1218: 1215: 1213: 1210: 1208: 1205: 1203: 1200: 1198: 1195: 1193: 1190: 1188: 1185: 1183: 1180: 1179: 1178: 1177: 1172: 1167: 1164: 1162: 1159: 1157: 1154: 1152: 1149: 1147: 1144: 1142: 1139: 1137: 1134: 1132: 1129: 1128: 1127: 1126: 1121: 1116: 1113: 1111: 1108: 1106: 1103: 1101: 1098: 1096: 1093: 1091: 1088: 1086: 1083: 1081: 1078: 1076: 1073: 1071: 1068: 1066: 1063: 1061: 1058: 1057: 1056: 1055: 1050: 1045: 1042: 1040: 1037: 1035: 1032: 1030: 1027: 1025: 1022: 1020: 1017: 1015: 1012: 1011: 1010: 1009: 1006: 1002: 992: 991: 984: 981: 979: 976: 974: 971: 969: 966: 964: 961: 959: 956: 954: 951: 949: 946: 944: 941: 939: 936: 934: 931: 929: 926: 924: 921: 919: 916: 914: 911: 909: 906: 904: 901: 899: 896: 894: 891: 889: 886: 884: 881: 879: 876: 874: 871: 869: 866: 864: 861: 859: 856: 854: 851: 849: 846: 844: 841: 839: 836: 834: 831: 829: 826: 824: 821: 819: 816: 814: 811: 809: 806: 804: 801: 799: 796: 794: 791: 789: 786: 784: 781: 780: 772: 771: 768: 764: 757: 754: 752: 749: 748: 743: 737: 736: 729: 726: 724: 721: 719: 716: 714: 711: 709: 706: 704: 701: 699: 696: 694: 691: 687: 684: 683: 682: 679: 678: 675: 672: 671: 667: 661: 660: 649: 646: 644: 643:Circumference 641: 639: 636: 635: 634: 633: 630: 626: 621: 618: 616: 613: 612: 611: 610: 607: 606:Quadrilateral 603: 598: 595: 593: 590: 588: 585: 583: 580: 579: 578: 577: 574: 573:Parallelogram 570: 565: 562: 560: 557: 555: 552: 551: 550: 549: 546: 542: 537: 534: 532: 529: 527: 524: 523: 522: 521: 515: 509: 508: 501: 498: 494: 491: 489: 486: 485: 484: 481: 480: 476: 470: 469: 462: 459: 458: 454: 448: 447: 440: 437: 435: 432: 430: 427: 426: 423: 420: 418: 415: 412: 411:Perpendicular 408: 407:Orthogonality 405: 403: 400: 398: 395: 393: 390: 389: 386: 383: 382: 381: 371: 368: 367: 362: 361: 352: 349: 348: 347: 344: 342: 339: 337: 334: 332: 331:Computational 329: 327: 324: 320: 317: 316: 315: 312: 310: 307: 305: 302: 298: 295: 293: 290: 288: 285: 284: 283: 280: 276: 273: 271: 268: 267: 266: 263: 261: 258: 256: 253: 251: 248: 246: 243: 241: 238: 234: 231: 227: 224: 223: 222: 219: 218: 217: 216:Non-Euclidean 214: 212: 209: 208: 204: 198: 197: 190: 186: 183: 181: 178: 177: 175: 174: 170: 166: 162: 157: 153: 152: 149: 145: 135: 133: 129: 123: 121: 117: 114: 109: 107: 103: 100: 99:Conic section 97: 93: 88: 79: 76: radius 70: 61: 50: 45: 40: 37: 33: 19: 8796:Cut-the-Knot 8784: 8773: 8758: 8726: 8695: 8662: 8654: 8640:cite journal 8628:. Retrieved 8601: 8597: 8587: 8562: 8558: 8552: 8533: 8514: 8495: 8487: 8482: 8474: 8466: 8458:the original 8432:(1530): 30. 8429: 8425: 8415: 8407: 8402: 8392: 8388: 8380: 8375: 8340: 8336: 8322: 8297: 8289: 8270: 8264: 8252:. Retrieved 8249:TheCollector 8248: 8238: 8226:. Retrieved 8222: 8213: 8194: 8178: 8169: 8158: 8150: 8135: 8116: 8083: 8079: 8069: 8064:, on Perseus 8061: 8046: 8022: 7947: 7900: 7881:Parry circle 7818: 7736: 7725: 7715: 7702: 7695: 7691: 7682: 7673: 7671: 7664: 7514: 7510: 7506: 7467: 7461: 7325: 7166: 7163: 7156: 7150: 7146:superellipse 7133: 7090: 7076: 7054: 6763: 6745:Cassini oval 6735: 6729: 6725: 6720: 6716: 6712: 6631:superellipse 6619:weighted sum 6599: 6595: 6581: 6569: 6554: 6536:, such as a 6531: 6524: 6513: 6503: 6495: 6491: 6487: 6485: 6380: 6376: 6372: 6370: 6354: 6352: 6284: 6280: 6276: 6272: 6266: 6263:Cross-ratios 6258: 6253: 6249: 6245: 6241: 6237: 6233: 6229: 6225: 6221: 6217: 6215: 6148: 6141: 6133: 6129: 6125: 6121: 6117: 6115: 6113:two points. 6110: 6106: 6102: 6098: 6094: 6089: 6079: 6072: 6047: 6041: 6035: 6029: 6016: 6006: 5991: 5977: 5971: 5965: 5941: 5932: 5913: 5906: 5896: 5890: 5886: 5882: 5878: 5871: 5867: 5861: 5857: 5855: 5790: 5786: 5784: 5773: 5749: 5724: 5655:). That is, 5588: 5581: 5577: 5571: 5567: 5551: 5547: 5543: 5538: 5534: 5530: 5526: 5522: 5514: 5510: 5506: 5502: 5497: 5493: 5489: 5485: 5477: 5473: 5469: 5465: 5460: 5456: 5452: 5422: 5402: 5396: 5392: 5388: 5381: 5377: 5373: 5369: 5365: 5361: 5335: 5331: 5327: 5323: 5315: 5311: 5307: 5303: 5298: 5294: 5290: 5286: 5278: 5274: 5269: 5265: 5261: 5257: 5196:line segment 5169:circumcircle 5151:great circle 5117:proportional 5102: 5100:circle group 5095: 4930: 4923: 4832: 4825: 4822: 4565: 4558: 4551: 4546: 4542: 4538: 4531: 4527: 4523: 4516: 4507: 4500: 4496: 4492: 4488: 4484: 4480: 4471: 4464: 4458: 4454: 4451:tangent line 4448: 4221: 4220:and complex 4217: 4213: 4211: 4143: 4093: 4044: 4040: 4034: 3904: 3902: 3844: 3837: 3831: 3827: 3817: 3812: 3808: 3801: 3726: 3724: 3617: 3603: 3599: 3595: 3591: 3585: 3483: 2982: 2869: 2866:3-point form 2859: 2851: 2843: 2839: 2837: 2692: 2690: axis. 2687: 2683: 2679: 2675: 2671: 2655: 2552: 2487: 2483: 2479: 2475: 2467: 2461: 2380:) such that 2377: 2373: 2369: 2365: 2361: 2350: 2346: 2344: 2333: 2329: 2325: 2299: 2232: 2190: 2164: 2098: 2086: 2081: 1998: 1996: 1928: 1857: 1853: 1849: 1829: 1801:Dharma wheel 1797: 1793: 1760:abstract art 1757: 1743:proved that 1739:In 1880 CE, 1738: 1711: 1690: 1683: 1679: 1650: 1623: 1618:astronomical 1585: 1579: 1575: 1566:), itself a 1563: 1555: 1553: 1517: 1513: 1511: 1487: 1331: 1298: 1296: 1115:Parameshvara 928:Parameshvara 698:Dodecahedron 628: 282:Differential 86: 77: 68: 59: 36: 8604:: 335–355. 8331:divided by 8254:28 December 8228:28 December 7814:Woo circles 7794:Ford circle 7721:hypersphere 6572:hypocycloid 6269:cross-ratio 5756:right angle 5155:unit sphere 5144:unit circle 4043:and radius 2358:coordinates 2123:, then the 1634:petroglyphs 1356:Terminology 1240:Present day 1187:Lobachevsky 1174:1700s–1900s 1131:Jyeṣṭhadeva 1123:1400s–1700s 1075:Brahmagupta 898:Lobachevsky 878:Jyeṣṭhadeva 828:Brahmagupta 756:Hypersphere 728:Tetrahedron 703:Icosahedron 275:Diophantine 8807:Categories 8744:PlanetMath 8674:0486406806 8611:2010.12340 8038:References 7937:Of a torus 7121:pseudomath 7113:polynomial 6604:Archimedes 6502:of points 6365:See also: 6060:See also: 5736:See also: 5444:See also: 5066:Properties 3602:(1: − 2557:using the 2241:of radius 2117:arc length 1931:Archimedes 1836:irrational 1680:Book 3 of 1568:metathesis 1500:Semicircle 1366:concentric 1100:al-Yasamin 1044:Apollonius 1039:Archimedes 1029:Pythagoras 1019:Baudhayana 973:al-Yasamin 923:Pythagoras 818:Baudhayana 808:Archimedes 803:Apollonius 708:Octahedron 559:Hypotenuse 434:Similarity 429:Congruence 341:Incidence 292:Symplectic 287:Riemannian 270:Arithmetic 245:Projective 233:Hyperbolic 161:Projecting 8760:MathWorld 8733:EMS Press 8700:. Dover. 8350:1303.0904 8108:130296519 8100:0003-598X 8080:Antiquity 7968:Apeirogon 7642:θ 7639:⁡ 7620:θ 7617:⁡ 7525:π 7415:⋯ 7262:⋯ 7132:In other 7082:geometers 7007:− 6998:… 6911:∑ 6540:, is any 6514:In every 6486:Thus, if 6136:. By the 6022:collinear 5700:∠ 5697:− 5683:∠ 5666:∠ 5641:⌢ 5609:⌢ 5024:− 4901:− 4883:− 4867:− 4787:− 4772:− 4747:− 4732:− 4680:− 4645:− 4617:− 4589:− 4417:¯ 4401:¯ 4390:− 4382:¯ 4374:− 4369:¯ 4340:− 4292:− 4265:¯ 4257:− 4212:for real 4190:¯ 4163:¯ 4063:− 4007:ϕ 4004:− 4001:θ 3995:⁡ 3967:− 3952:± 3946:ϕ 3943:− 3940:θ 3934:⁡ 3907:, giving 3883:ϕ 3880:− 3877:θ 3871:⁡ 3785:ϕ 3746:θ 3674:ϕ 3671:− 3668:θ 3662:⁡ 3640:− 3598:: 0) and 3538:− 3523:− 3446:− 3417:− 3401:− 3385:− 3356:− 3325:− 3296:− 3264:− 3235:− 3197:− 3171:− 3158:− 3142:− 3116:− 3088:− 3062:− 3033:− 3007:− 2730:− 2632:⁡ 2596:⁡ 2419:− 2394:− 2311:Equations 2273:θ 2245:and with 2213:θ 2184:, or one 2135:θ 2048:≈ 2029:π 1970:π 1933:, in his 1886:π 1877:π 1834:(pi), an 1682:Euclid's 1554:The word 1550:Etymology 1376:connected 1346:astronomy 1334:full moon 1217:Minkowski 1136:Descartes 1070:Aryabhata 1065:Kātyāyana 996:by period 908:Minkowski 883:Kātyāyana 843:Descartes 788:Aryabhata 767:Geometers 751:Tesseract 615:Trapezoid 587:Rectangle 380:Dimension 265:Algebraic 255:Synthetic 226:Spherical 211:Euclidean 132:Perimeter 53:A circle 8755:"Circle" 8735:. 2001 . 8723:"Circle" 8624:Archived 8579:12641658 8541:Archived 8522:Archived 8503:Archived 8202:Archived 8183:Archived 8144:7227282M 8124:Archived 8054:Archived 8028:𝜏 (tau) 7957:See also 7846:Incircle 7841:Excircle 7728:topology 7676:for the 7505:, where 7501:using a 7344:‖ 7338:‖ 7187:‖ 7181:‖ 7117:rational 6527:vertices 6520:incircle 6516:triangle 6086:constant 5929:midpoint 5723:, where 5576:, where 5432:Theorems 5330:, where 4324:, since 2464:equation 2115:with an 1839:constant 1784:Creation 1726:geometry 1706:Elements 1695:—  1684:Elements 1620:drawing. 1574:κρίκος ( 1404:Diameter 1368:circles. 1350:calculus 1323:diameter 1207:Poincaré 1151:Minggatu 1110:Yang Hui 1080:Virasena 968:Yang Hui 963:Virasena 933:Poincaré 913:Minggatu 693:Cylinder 638:Diameter 597:Rhomboid 554:Altitude 545:Triangle 439:Symmetry 417:Parallel 402:Diagonal 372:Features 369:Concepts 260:Analytic 221:Elliptic 203:Branches 189:Timeline 148:Geometry 18:1-Sphere 8813:Circles 8454:4030420 8434:Bibcode 8367:3413900 8174:Proclus 7472:squares 7111:of any 7099:) is a 7079:ancient 6755:figure. 6623:ellipse 5916:compass 5780:versine 5776:sagitta 5762:Sagitta 5565:, then 5463:, then 5419:⁠ 5407:⁠ 5395:and if 5346:Tangent 5301:, then 5272:, then 5252:If the 5153:of the 5110:similar 5090:is the 4035:In the 3835:. When 3488:, each 2682:,  2674:,  2482:| and | 2332:,  2182:degrees 2167:subtend 1780:compass 1722:science 1692:centre. 1669:⁠ 1657:⁠ 1594:History 1587:circuit 1570:of the 1506:Tangent 1488:segment 1484:Segment 1362:Annulus 1232:Coxeter 1212:Hilbert 1197:Riemann 1146:Huygens 1105:al-Tusi 1095:Khayyám 1085:Alhazen 1052:1–1400s 953:al-Tusi 938:Riemann 888:Khayyám 873:Huygens 868:Hilbert 838:Coxeter 798:Alhazen 776:by name 713:Pyramid 592:Rhombus 536:Polygon 488:segment 336:Fractal 319:Digital 304:Complex 185:History 180:Outline 137:C = 2πR 8740:Circle 8704:  8671:  8630:17 May 8577:  8452:  8426:Nature 8365:  8310:  8277:  8164:(1959) 8142:  8106:  8098:  8051:krikos 7998:Sphere 7948: 7688:metric 7136:-norms 6977:  6719:, and 6494:, and 6279:, and 6236:is on 6232:where 5228:, the 5224:For a 4499:) to ( 4273:  4248:  3725:where 2678:) to ( 2654:where 2345:In an 2302:𝜃 = 2 2125:radian 2107:of an 2105:vertex 2095:Radian 2051:0.7854 1937:, the 1702:Book I 1698:Euclid 1615:Arabic 1581:circus 1576:krikos 1556:circle 1518:closed 1494:Secant 1478:Sector 1422:Radius 1398:length 1396:: the 1382:Centre 1374:: any 1319:radius 1315:centre 1307:points 1299:circle 1253:Gromov 1248:Atiyah 1227:Veblen 1222:Cartan 1192:Bolyai 1161:Sakabe 1141:Pascal 1034:Euclid 1024:Manava 958:Veblen 943:Sakabe 918:Pascal 903:Manava 863:Gromov 848:Euclid 833:Cartan 823:Bolyai 813:Atiyah 723:Sphere 686:cuboid 674:Volume 629:Circle 582:Square 500:Length 422:Vertex 326:Convex 309:Finite 250:Affine 165:sphere 83:  74:  65:  56:  42:Circle 8606:arXiv 8575:S2CID 8450:S2CID 8345:arXiv 8104:S2CID 8014:Notes 7169:-norm 7115:with 6626:zero. 6594:with 6500:locus 6111:about 6095:ratio 5380:and ∠ 5176:Chord 4463:P = ( 4461:. If 2668:angle 2658:is a 2462:This 2237:of a 2109:angle 1714:Plato 1560:Greek 1470:is a 1388:Chord 1342:gears 1338:wheel 1311:plane 1309:in a 1303:shape 1301:is a 1202:Klein 1182:Gauss 1156:Euler 1090:Sijzi 1060:Zhang 1014:Ahmes 978:Zhang 948:Sijzi 893:Klein 858:Gauss 853:Euler 793:Ahmes 526:Plane 461:Point 397:Curve 392:Angle 169:plane 167:to a 8702:ISBN 8669:ISBN 8646:link 8632:2021 8308:ISBN 8275:ISBN 8256:2023 8230:2023 8096:ISSN 7701:and 7109:root 6949:> 6120:and 6101:and 5975:and 5893:/ 2) 5774:The 5623:and 5537:and 5496:and 5488:and 5455:and 5421:arc( 5297:and 5289:and 5268:and 5260:and 5194:The 5184:The 5133:and 5124:area 5122:The 5094:O(2, 4449:The 4433:line 3594:(1: 2186:turn 1860:by: 1788:halo 1778:The 1728:and 1636:and 1628:and 1584:and 1514:open 1416:Lens 1410:Disc 1348:and 1327:disc 1166:Aida 783:Aida 742:Four 681:Cube 648:Area 620:Kite 531:Area 483:Line 120:Area 112:O(2) 95:Type 8742:at 8616:doi 8567:doi 8563:110 8442:doi 8355:doi 8304:108 8088:doi 7744:). 7726:In 7636:cos 7614:sin 7462:In 6738:= 2 6606:to 6371:If 6250:CPD 6242:CPD 6230:BPQ 6224:on 6149:APB 6045:or 5889:= ( 5403:DAQ 5387:If 5382:BPA 5378:BOA 5326:− 4 4823:If 4711:or 4530:+ ( 3986:sin 3931:cos 3868:cos 3823:= 0 3659:cos 3618:In 3484:In 2842:to 2629:sin 2593:cos 2119:of 2084:). 1747:is 1716:'s 1712:In 1660:256 1372:Arc 1005:BCE 493:ray 8828:Pi 8809:: 8794:. 8783:. 8772:. 8757:. 8731:. 8725:. 8642:}} 8638:{{ 8614:. 8602:11 8600:. 8596:. 8573:. 8561:. 8473:, 8448:. 8440:. 8430:59 8428:. 8424:. 8363:MR 8361:. 8353:. 8341:46 8339:. 8306:. 8247:. 8221:. 8176:, 8157:, 8140:OL 8102:. 8094:. 8084:87 8082:. 8078:. 7466:, 7160:). 7088:. 7052:. 6750:A 6743:A 6728:= 6715:, 6629:A 6613:A 6570:A 6567:. 6555:A 6532:A 6529:. 6490:, 6377:AB 6339:1. 6275:, 6254:CD 6238:AP 6226:AB 6218:PD 6142:PC 6134:AB 6107:AB 6039:, 6024:). 6007:PR 5992:PQ 5969:, 5881:− 5870:− 5574:√2 5570:= 5552:AD 5550:× 5548:AC 5546:= 5544:AF 5515:AE 5513:× 5511:AB 5509:= 5507:AD 5505:× 5503:AC 5490:AD 5486:AE 5478:AE 5476:× 5474:AB 5472:= 5470:AD 5468:× 5466:AC 5457:EB 5453:CD 5423:AQ 5405:= 5397:AQ 5389:AD 5314:+ 5310:+ 5306:+ 5279:cd 5277:= 5275:ab 5241:). 5221:. 5146:. 5112:. 5075:). 4928:. 4831:≠ 4557:, 4545:= 4537:– 4522:− 4506:, 4495:, 4483:, 4470:, 4435:. 4216:, 3843:= 3830:= 3610:. 3572:0. 2986:: 2486:− 2478:− 2376:, 2364:, 2188:. 2091:. 2001:, 1811:. 1704:, 1700:, 1677:. 1666:81 1648:. 1646:Bi 1352:. 1329:. 1297:A 163:a 125:πR 8798:. 8763:. 8746:. 8710:. 8677:. 8648:) 8634:. 8618:: 8608:: 8581:. 8569:: 8444:: 8436:: 8369:. 8357:: 8347:: 8333:d 8329:C 8316:. 8283:. 8258:. 8232:. 8110:. 8090:: 8030:. 7737:R 7706:∞ 7703:L 7699:1 7696:L 7692:r 7686:∞ 7683:L 7680:( 7674:r 7646:| 7632:| 7628:+ 7624:| 7610:| 7605:1 7600:= 7597:r 7577:1 7574:= 7570:| 7566:y 7562:| 7558:+ 7554:| 7550:x 7546:| 7515:r 7511:r 7507:r 7489:r 7484:2 7468:p 7448:. 7441:2 7436:| 7431:n 7427:x 7423:| 7418:+ 7412:+ 7407:2 7402:| 7397:2 7393:x 7389:| 7384:+ 7379:2 7374:| 7369:1 7365:x 7361:| 7354:= 7349:2 7341:x 7326:p 7312:. 7307:p 7303:/ 7299:1 7294:) 7288:p 7283:| 7278:n 7274:x 7270:| 7265:+ 7259:+ 7254:p 7249:| 7244:2 7240:x 7236:| 7231:+ 7226:p 7221:| 7216:1 7212:x 7208:| 7202:( 7197:= 7192:p 7184:x 7167:p 7157:p 7151:p 7134:p 7097:π 7038:n 7034:P 7013:; 7010:1 7004:n 7001:, 6995:, 6992:2 6989:, 6986:1 6983:= 6980:m 6968:, 6963:m 6960:2 6956:R 6952:n 6944:m 6941:2 6936:i 6932:d 6926:n 6921:1 6918:= 6915:i 6890:R 6868:i 6864:d 6843:m 6840:2 6818:n 6814:P 6793:n 6772:n 6740:. 6736:n 6730:a 6726:b 6721:n 6717:b 6713:a 6699:1 6696:= 6690:n 6685:| 6680:b 6677:y 6672:| 6667:+ 6661:n 6656:| 6651:a 6648:x 6643:| 6610:. 6600:n 6596:n 6504:P 6496:C 6492:B 6488:A 6467:| 6463:C 6460:B 6456:| 6449:| 6445:C 6442:A 6438:| 6431:= 6424:| 6420:P 6417:B 6413:| 6406:| 6402:P 6399:A 6395:| 6381:P 6373:C 6355:P 6336:= 6331:| 6326:] 6323:P 6320:, 6317:C 6314:; 6311:B 6308:, 6305:A 6302:[ 6297:| 6285:P 6281:C 6277:B 6273:A 6246:P 6234:Q 6222:D 6202:. 6196:C 6193:B 6188:C 6185:A 6179:= 6173:P 6170:B 6165:P 6162:A 6130:C 6126:P 6122:B 6118:A 6103:B 6099:A 6083:2 6080:d 6078:/ 6076:1 6073:d 6048:R 6042:Q 6036:P 6030:M 6017:M 6011:. 5996:. 5981:, 5978:R 5972:Q 5966:P 5942:M 5933:M 5897:r 5891:y 5887:x 5885:) 5883:x 5879:r 5877:2 5872:x 5868:r 5866:2 5862:x 5858:y 5842:. 5837:2 5834:x 5829:+ 5823:x 5820:8 5814:2 5810:y 5804:= 5801:r 5791:x 5787:y 5725:O 5710:C 5707:O 5704:B 5693:E 5690:O 5687:D 5680:= 5676:B 5673:A 5670:C 5663:2 5637:C 5634:B 5605:E 5602:D 5589:A 5582:r 5578:ℓ 5572:r 5568:ℓ 5563:° 5539:D 5535:C 5531:A 5527:F 5523:A 5498:C 5494:B 5481:. 5461:A 5427:. 5425:) 5416:2 5413:/ 5410:1 5401:∠ 5393:A 5374:O 5370:P 5366:B 5362:A 5336:p 5332:r 5328:p 5324:r 5316:d 5312:c 5308:b 5304:a 5299:d 5295:c 5291:b 5287:a 5282:. 5270:d 5266:c 5262:b 5258:a 5171:. 5161:. 5135:π 5131:π 5119:. 5105:. 5103:T 5096:R 5051:. 5044:1 5040:y 5034:1 5030:x 5021:= 5015:x 5012:d 5007:y 5004:d 4981:, 4976:2 4972:r 4968:= 4965:y 4960:1 4956:y 4952:+ 4949:x 4944:1 4940:x 4910:. 4904:b 4896:1 4892:y 4886:a 4878:1 4874:x 4864:= 4858:x 4855:d 4850:y 4847:d 4833:b 4829:1 4826:y 4809:. 4804:2 4800:r 4796:= 4793:) 4790:b 4784:y 4781:( 4778:) 4775:b 4767:1 4763:y 4759:( 4756:+ 4753:) 4750:a 4744:x 4741:( 4738:) 4735:a 4727:1 4723:x 4719:( 4699:, 4694:1 4690:y 4686:) 4683:b 4675:1 4671:y 4667:( 4664:+ 4659:1 4655:x 4651:) 4648:a 4640:1 4636:x 4632:( 4629:= 4626:y 4623:) 4620:b 4612:1 4608:y 4604:( 4601:+ 4598:x 4595:) 4592:a 4584:1 4580:x 4576:( 4566:c 4562:1 4559:y 4555:1 4552:x 4547:c 4543:y 4541:) 4539:b 4535:1 4532:y 4528:x 4526:) 4524:a 4520:1 4517:x 4515:( 4511:1 4508:y 4504:1 4501:x 4497:b 4493:a 4489:r 4485:b 4481:a 4477:) 4475:1 4472:y 4468:1 4465:x 4459:P 4455:P 4414:c 4409:c 4406:+ 4398:z 4393:c 4387:z 4379:c 4366:z 4361:z 4358:= 4353:2 4348:| 4343:c 4337:z 4333:| 4310:2 4305:| 4300:c 4296:| 4287:2 4283:r 4279:= 4276:q 4270:, 4262:c 4254:= 4251:g 4245:, 4242:1 4239:= 4236:p 4222:g 4218:q 4214:p 4198:q 4195:= 4186:z 4183:g 4177:+ 4174:z 4171:g 4168:+ 4160:z 4155:z 4152:p 4130:. 4127:c 4124:+ 4119:t 4116:i 4112:e 4108:r 4105:= 4102:z 4080:. 4077:r 4074:= 4070:| 4066:c 4060:z 4056:| 4045:r 4041:c 4015:. 4010:) 3998:( 3990:2 3980:2 3975:0 3971:r 3962:2 3958:a 3949:) 3937:( 3926:0 3922:r 3918:= 3915:r 3905:r 3889:. 3886:) 3874:( 3865:a 3862:2 3859:= 3856:r 3845:a 3841:0 3838:r 3832:a 3828:r 3821:0 3818:r 3813:x 3809:φ 3805:0 3802:r 3788:) 3782:, 3777:0 3773:r 3769:( 3749:) 3743:, 3740:r 3737:( 3727:a 3711:, 3706:2 3702:a 3698:= 3693:2 3688:0 3684:r 3680:+ 3677:) 3665:( 3654:0 3650:r 3646:r 3643:2 3635:2 3631:r 3604:i 3600:J 3596:i 3592:I 3569:= 3564:2 3560:z 3556:c 3553:+ 3550:z 3547:y 3544:b 3541:2 3535:z 3532:x 3529:a 3526:2 3518:2 3514:y 3510:+ 3505:2 3501:x 3465:. 3459:) 3454:1 3450:x 3441:3 3437:x 3433:( 3430:) 3425:2 3421:y 3412:3 3408:y 3404:( 3398:) 3393:2 3389:x 3380:3 3376:x 3372:( 3369:) 3364:1 3360:y 3351:3 3347:y 3343:( 3338:) 3333:2 3329:y 3320:3 3316:y 3312:( 3309:) 3304:1 3300:y 3291:3 3287:y 3283:( 3280:+ 3277:) 3272:2 3268:x 3259:3 3255:x 3251:( 3248:) 3243:1 3239:x 3230:3 3226:x 3222:( 3216:= 3210:) 3205:1 3201:x 3192:x 3187:( 3184:) 3179:2 3175:y 3166:y 3161:( 3155:) 3150:2 3146:x 3137:x 3132:( 3129:) 3124:1 3120:y 3111:y 3106:( 3101:) 3096:2 3092:y 3083:y 3078:( 3075:) 3070:1 3066:y 3057:y 3052:( 3049:+ 3046:) 3041:2 3037:x 3028:x 3023:( 3020:) 3015:1 3011:x 3002:x 2997:( 2968:) 2963:3 2959:y 2955:, 2950:3 2946:x 2942:( 2939:, 2936:) 2931:2 2927:y 2923:, 2918:2 2914:x 2910:( 2907:, 2904:) 2899:1 2895:y 2891:, 2886:1 2882:x 2878:( 2860:t 2852:x 2844:r 2840:t 2820:. 2812:2 2808:t 2804:+ 2801:1 2796:t 2793:2 2787:r 2784:+ 2781:b 2778:= 2771:y 2764:, 2756:2 2752:t 2748:+ 2745:1 2738:2 2734:t 2727:1 2721:r 2718:+ 2715:a 2712:= 2705:x 2688:x 2684:y 2680:x 2676:b 2672:a 2664:π 2656:t 2638:, 2635:t 2625:r 2622:+ 2619:b 2616:= 2609:y 2602:, 2599:t 2589:r 2586:+ 2583:a 2580:= 2573:x 2534:. 2529:2 2525:r 2521:= 2516:2 2512:y 2508:+ 2503:2 2499:x 2488:b 2484:y 2480:a 2476:x 2448:. 2443:2 2439:r 2435:= 2430:2 2426:) 2422:b 2416:y 2413:( 2410:+ 2405:2 2401:) 2397:a 2391:x 2388:( 2378:y 2374:x 2370:r 2366:b 2362:a 2360:( 2351:y 2349:– 2347:x 2334:b 2330:a 2326:r 2304:π 2286:. 2281:2 2277:r 2268:2 2265:1 2260:= 2257:A 2243:r 2235:A 2219:, 2216:r 2210:= 2207:s 2197:r 2193:s 2177:π 2175:2 2151:. 2146:r 2143:s 2138:= 2121:s 2101:r 2082:d 2064:, 2059:2 2055:d 2043:4 2037:2 2033:d 2023:= 2019:a 2016:e 2013:r 2010:A 1999:d 1983:. 1978:2 1974:r 1967:= 1963:a 1960:e 1957:r 1954:A 1943:π 1917:π 1892:. 1889:d 1883:= 1880:r 1874:2 1871:= 1868:C 1858:d 1854:r 1850:C 1845:π 1843:2 1832:π 1790:. 1745:π 1674:π 1663:/ 1458:0 1455:= 1452:r 1432:r 1286:e 1279:t 1272:v 413:) 409:( 191:) 187:( 87:O 78:R 69:D 60:C 34:. 20:)

Index

1-Sphere
Circle (disambiguation)

Conic section
Symmetry group
O(2)
Area
Perimeter
Geometry
Stereographic projection from the top of a sphere onto a plane beneath it
Projecting
sphere
plane
Outline
History
Timeline
Branches
Euclidean
Non-Euclidean
Elliptic
Spherical
Hyperbolic
Non-Archimedean geometry
Projective
Affine
Synthetic
Analytic
Algebraic
Arithmetic
Diophantine

Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.