Knowledge (XXG)

Euler line

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20: 1142: 908: 919: 642: 3899:; and there is a circumsphere passing through all of the vertices, whose center is the circumcenter. These points define the "Euler line" of a tetrahedron analogous to that of a triangle. The centroid is the midpoint between its Monge point and circumcenter along this line. The center of the 3629: 1137:{\displaystyle 3\cdot {\vec {GO}}=\left(\sum \limits _{\scriptstyle {\rm {cyc}}}{\vec {GA}}\right)+\left(\sum \limits _{\scriptstyle {\rm {cyc}}}{\vec {AO}}\right)=0-\left(\sum \limits _{\scriptstyle {\rm {cyc}}}{\vec {OA}}\right)=-{\vec {OH}}.} 903:{\displaystyle {\vec {GO}}={\vec {GA}}+{\vec {AO}}\,{\mbox{(in triangle }}AGO{\mbox{)}},\,{\vec {GO}}={\vec {GB}}+{\vec {BO}}\,{\mbox{(in triangle }}BGO{\mbox{)}},\,{\vec {GO}}={\vec {GC}}+{\vec {CO}}\,{\mbox{(in triangle }}CGO{\mbox{)}}.} 2211: 3357: 184:, although it had not been defined in Euler's time. In equilateral triangles, these four points coincide, but in any other triangle they are all distinct from each other, and the Euler line is determined by any two of them. 2897: 2517: 2392: 3045: 2740: 2051: 1852: 1643: 631: 527: 1484: 447: 1743: 1205: 3715:—that is, it goes through both the right-angled vertex and the midpoint of the side opposite that vertex. This is because the right triangle's orthocenter, the intersection of its 3433: 2089: 2592: 2273: 1278:
are put together into a single proof. However, most of the proofs of the problem of Sylvester rely on the fundamental properties of free vectors, independently of the Euler line.
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It is well known that the incenter of a Euclidean triangle lies on its Euler line connecting the centroid and the circumcenter if and only if the triangle is isosceles
1381: 1342: 3175: 3145: 3116: 3202: 3074: 2923: 2766: 2618: 4788: 4156: 3919:(plural of simplex). For example, every polygon is a simplicial polytope. The Euler line associated to such a polytope is the line determined by its centroid and 267: 4199: 4179: 4130: 4110: 4087: 4067: 4047: 4027: 4007: 3984: 3964: 3944: 1265: 1245: 1225: 474: 364: 336: 313: 290: 2097: 3210: 2777: 2400: 2278: 2934: 2629: 1901: 4734: 2057: 222:
at the reference triangle's vertices. The circumcenter of the tangential triangle lies on the Euler line of the reference triangle. The
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Dörrie, Heinrich, "100 Great Problems of Elementary Mathematics. Their History and Solution". Dover Publications, Inc., New York, 1965,
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Wladimir G. Boskoff, Laurent¸iu Homentcovschi, and Bogdan D. Suceava, "Gossard's Perspector and Projective Consequences",
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Furthermore, the squared distance between the centroid and the circumcenter along the Euler line is less than the squared
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are in the same proportions, though in the opposite order, as the sides) is perpendicular to one of the medians.
3363: 3895:. Seven lines associated with a tetrahedron are concurrent at its centroid; its six midplanes intersect at its 211:, for which the Euler line coincides with the symmetry axis of the triangle and contains all triangle centers. 3888: 2062: 128:
of the triangle, and it passes through several important points determined from the triangle, including the
125: 2544: 4328: 2228: 1391: 3624:{\displaystyle m_{E}=-{\frac {m_{1}m_{2}+m_{1}m_{3}+m_{2}m_{3}+3}{m_{1}+m_{2}+m_{3}+3m_{1}m_{2}m_{3}}}.} 1892: 1401:
of the nine-point circle lies along the Euler line midway between the orthocenter and the circumcenter:
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Tabachnikov, Serge; Tsukerman, Emmanuel (May 2014), "Circumcenter of Mass and Generalized Euler Line",
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inscribed in a given triangle is formed by two lines perpendicular to the given triangle's Euler line.
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Edmonds, Allan L.; Hajja, Mowaffaq; Martini, Horst (2008), "Orthocentric simplices and biregularity",
4380: 3920: 3687: 3641: 270: 223: 121: 4739: 4695: 4669: 4499: 4279:, ser. I, vol. XXVI, pp. 139–157, Societas Scientiarum Naturalium Helveticae, Lausanne, 1953, 3912: 3900: 3814: 3752: 3716: 3440:
Thus the slope of the Euler line (if finite) is expressible in terms of the slopes of the sides as
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A triangle's Kiepert parabola is the unique parabola that is tangent to the sides (two of them
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The concept of a triangle's Euler line extends to the Euler line of other shapes, such as the
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every point on the Euler line, except the orthocenter, is given by the trilinear coordinates
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Francisco Javier Garc ́ıa Capita ́n, "Locus of Centroids of Similar Inscribed Triangles",
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Euler showed in 1765 that in any triangle, the orthocenter, circumcenter and centroid are
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Scimemi, Benedetto, "Simple Relations Regarding the Steiner Inellipse of a Triangle",
4568: 2206:{\displaystyle (\tan C-\tan B)\alpha +(\tan A-\tan C)\beta +(\tan B-\tan A)\gamma =0.} 4782: 4409: 4357: 4210: 3839: 152: 4627: 4708: 4466:
Scott, J.A., "Some examples of the use of areal coordinates in triangle geometry",
4287: 3719:, falls on the right-angled vertex while its circumcenter, the intersection of its 2538: 1521: 219: 196: 141: 133: 69: 4660:
An interactive applet showing several triangle centers that lies on the Euler line
19: 3352:{\displaystyle m_{1}m_{2}+m_{1}m_{3}+m_{1}m_{E}+m_{2}m_{3}+m_{2}m_{E}+m_{3}m_{E}} 1489:
Thus the Euler line could be repositioned on a number line with the circumcenter
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of the triangle with vertices at the other three points) are concurrent at the
2892:{\displaystyle \cos A+2\cos B\cos C:\cos B+2\cos C\cos A:\cos C+2\cos A\cos B,} 4743: 4619: 4393: 4378:
Leversha, Gerry; Smith, G. C. (November 2007), "Euler and triangle geometry",
4341: 3712: 2512:{\displaystyle \cos A+t\cos B\cos C:\cos B+t\cos C\cos A:\cos C+t\cos A\cos B} 2387:{\displaystyle \sec A:\sec B:\sec C=\cos B\cos C:\cos C\cos A:\cos A\cos B),} 4769: 4659: 3858: 3720: 3040:{\displaystyle \cos A-\cos B\cos C:\cos B-\cos C\cos A:\cos C-\cos A\cos B,} 2735:{\displaystyle \cos A+\cos B\cos C:\cos B+\cos C\cos A:\cos C+\cos A\cos B,} 2046:{\displaystyle \sin(2A)\sin(B-C)x+\sin(2B)\sin(C-A)y+\sin(2C)\sin(A-B)z=0.} 1527:
by an amount equal to one-ninth the sum of the squares of the side lengths
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generally does not lie on the Euler line; it is on the Euler line only for
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and is twice as far from the orthocenter as it is from the circumcenter:
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Geometry Turned On: Dynamic Software in Learning, Teaching, and Research
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Kimberling, Clark (1998). "Triangle centers and central triangles".
68: Perpendicular lines from the side midpoints (intersect at the 4516:
Parry, C. F. (1991), "Steiner–Lehmus and the automedian triangle",
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Another way to represent the Euler line is in terms of a parameter
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Moreover, the Euler line is parallel to an acute triangle's side
1847:{\displaystyle GH^{2}=4R^{2}-{\tfrac {4}{9}}(a^{2}+b^{2}+c^{2}).} 3788:. The Euler lines of the 10 triangles with vertices chosen from 1638:{\displaystyle GO^{2}=R^{2}-{\tfrac {1}{9}}(a^{2}+b^{2}+c^{2}).} 626:{\displaystyle {\vec {OH}}={\vec {OA}}+{\vec {OB}}+{\vec {OC}}.} 4267:
Novi Commentarii Academiae Scientarum Imperialis Petropolitanae
3923:. This definition of an Euler line generalizes the ones above. 4265:[Easy solution of some difficult geometric problems]. 3879:
Tetrahedron § Properties analogous to those of a triangle
2225:. Starting with the circumcenter (with trilinear coordinates 913:
By adding these three relations, term by term, we obtain that
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denote the vertex angles of the reference triangle, and let
522:{\displaystyle {\frac {1}{3}}:{\frac {1}{3}}:{\frac {1}{3}}} 187:
Other notable points that lie on the Euler line include the
4437:, Dover Publications, 2007 (orig. Barnes & Noble 1952). 4556:
http://forumgeom.fau.edu/FG2009volume9/FG200924index.html
4305:. The Mathematical Association of America. pp. 3–4. 4550:
Beluhov, Nikolai Ivanov. "Ten concurrent Euler lines",
1788: 1579: 1479:{\displaystyle ON=NH,\quad OG=2\cdot GN,\quad NH=3GN.} 1069: 1011: 959: 891: 875: 806: 790: 721: 705: 442:{\displaystyle {\vec {GA}}+{\vec {GB}}+{\vec {GC}}=0.} 4687:
The quasi-Euler line of a quadrilateral and a hexagon
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http://forumgeom.fau.edu/FG2016volume16/FG201631.pdf
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and tangential triangles is also on the Euler line.
101: 3813:The Euler lines of the four triangles formed by an 3723:of sides, falls on the midpoint of the hypotenuse. 218:of a reference triangle is tangent to the latter's 95: 4193: 4173: 4150: 4124: 4104: 4081: 4061: 4041: 4021: 4001: 3978: 3958: 3938: 3671: 3623: 3427: 3351: 3196: 3169: 3139: 3110: 3088:, denote the slopes of the sides of a triangle as 3068: 3039: 2917: 2891: 2760: 2734: 2612: 2586: 2511: 2386: 2267: 2205: 2083: 2045: 1846: 1738:{\displaystyle OH^{2}=9R^{2}-(a^{2}+b^{2}+c^{2});} 1737: 1637: 1478: 1375: 1336: 1259: 1239: 1219: 1199: 1136: 902: 625: 521: 468: 441: 358: 330: 307: 284: 261: 4213:) of the triangle and has the Euler line as its 3763:Systems of triangles with concurrent Euler lines 2526:of the trilinears of these two points, for some 346:. We start by stating the prerequisites. First, 636:Now, using the vector addition, we deduce that 4679:Nine-point conic and Euler line generalization 3204:. Then these slopes are related according to 1200:{\displaystyle 3\cdot {\vec {OG}}={\vec {OH}}} 8: 4299:Schattschneider, Doris; King, James (1997). 3817:(a set of four points such that each is the 269:be a triangle. A proof of the fact that the 3682:Relation to inscribed equilateral triangles 3428:{\displaystyle +3m_{1}m_{2}m_{3}m_{E}+3=0.} 3177:and denote the slope of its Euler line as 4609: 4186: 4166: 4137: 4117: 4097: 4074: 4054: 4034: 4014: 3994: 3971: 3951: 3931: 3643: 3609: 3599: 3589: 3573: 3560: 3547: 3529: 3519: 3506: 3496: 3483: 3473: 3466: 3454: 3448: 3407: 3397: 3387: 3377: 3365: 3343: 3333: 3320: 3310: 3297: 3287: 3274: 3264: 3251: 3241: 3228: 3218: 3212: 3188: 3182: 3158: 3152: 3128: 3122: 3099: 3093: 3052: 2936: 2904: 2779: 2747: 2631: 2599: 2546: 2402: 2280: 2230: 2099: 2064: 1903: 1895:; then an equation for the Euler line is 1832: 1819: 1806: 1787: 1778: 1762: 1753: 1723: 1710: 1697: 1681: 1665: 1656: 1623: 1610: 1597: 1578: 1569: 1556: 1547: 1409: 1350: 1311: 1252: 1232: 1212: 1181: 1180: 1161: 1160: 1152: 1115: 1114: 1087: 1086: 1071: 1070: 1068: 1029: 1028: 1013: 1012: 1010: 977: 976: 961: 960: 958: 930: 929: 921: 890: 874: 873: 857: 856: 837: 836: 817: 816: 815: 805: 789: 788: 772: 771: 752: 751: 732: 731: 730: 720: 704: 703: 687: 686: 667: 666: 647: 646: 644: 604: 603: 584: 583: 564: 563: 544: 543: 541: 509: 496: 483: 481: 461: 417: 416: 397: 396: 377: 376: 374: 351: 323: 300: 277: 248: 176:. This property is also true for another 4445: 4443: 4226: 2275:) and the orthocenter (with trilinears 2084:{\displaystyle \alpha :\beta :\gamma } 4789:Straight lines defined for a triangle 4478: 4476: 3861:in this order on the Euler line, and 3047:corresponding to the parameter value 2899:corresponding to the parameter value 2742:corresponding to the parameter value 2594:corresponding to the parameter value 2587:{\displaystyle \cos A:\cos B:\cos C,} 7: 4720:"Triangle centers on the Euler line" 4429: 4427: 4425: 4423: 4421: 4419: 4373: 4371: 4112:has a center of rotational symmetry 3707:, the Euler line coincides with the 2268:{\displaystyle \cos A:\cos B:\cos C} 452:This follows from the fact that the 4683:A further Euler line generalization 4597:Discrete and Computational Geometry 4234: 4232: 4230: 3915:is a polytope whose facets are all 1065: 1007: 955: 4670:"Non-Euclidean Triangle Continuum" 4161:3. If all but one of the sides of 4009:has a line of reflection symmetry 3966:is sensitive to the symmetries of 3891:object bounded by four triangular 2056:An equation for the Euler line in 1078: 1075: 1072: 1020: 1017: 1014: 968: 965: 962: 163:Triangle centers on the Euler line 14: 4744:"Triangles have a Magic Highway" 4201:is orthogonal to the last side. 3825:common to all of the triangles. 1493:at the location 0, the centroid 454:absolute barycentric coordinates 91: 16:Line constructed from a triangle 3739:. In an isosceles triangle the 3672:{\displaystyle \tan B\tan C=3.} 1454: 1429: 1291:On the Euler line the centroid 1267:(in this order) are collinear. 4674:Wolfram Demonstrations Project 3686:The locus of the centroids of 2378: 2191: 2167: 2158: 2134: 2125: 2101: 2031: 2019: 2010: 2001: 1986: 1974: 1965: 1956: 1941: 1929: 1920: 1911: 1838: 1799: 1729: 1690: 1629: 1590: 1191: 1171: 1125: 1097: 1039: 987: 940: 867: 847: 827: 782: 762: 742: 697: 677: 657: 614: 594: 574: 554: 427: 407: 387: 1: 4704:Euler Line and 9-Point Circle 4486:, Volume 13 (2013), 169–184. 3946:is a polygon. The Euler line 3903:also lies on the Euler line. 4700:Altitudes and the Euler Line 3806:at the centroid of triangle 1501:, the nine-point center at 3 1295:is between the circumcenter 4470:83, November 1999, 472-477. 3086:Cartesian coordinate system 4805: 4567:Myakishev, Alexei (2006), 4433:Altshiller-Court, Nathan, 3876: 1207:, and so the three points 4691:Dynamic Geometry Sketches 4620:10.1007/s00454-014-9597-2 4394:10.1017/S0025557200182087 4342:10.1007/s00025-008-0294-4 3743:falls on the Euler line. 2217:Parametric representation 1287:Distances between centers 27: Euler's line, with 4518:The Mathematical Gazette 4181:have equal length, then 3773:Fermat–Torricelli points 3986:in the following ways: 3842:, the quasiorthocenter 3721:perpendicular bisectors 2058:barycentric coordinates 1891:be a variable point in 1376:{\displaystyle OH=3GO.} 1337:{\displaystyle GH=2GO;} 366:satisfies the relation 4554:9, 2009, pp. 271–274. 4329:Results in Mathematics 4241:Congressus Numerantium 4195: 4175: 4152: 4126: 4106: 4083: 4063: 4043: 4023: 4003: 3980: 3960: 3940: 3846:, the "area centroid" 3673: 3625: 3429: 3353: 3198: 3171: 3170:{\displaystyle m_{3},} 3141: 3140:{\displaystyle m_{2},} 3112: 3111:{\displaystyle m_{1},} 3070: 3041: 2919: 2893: 2762: 2736: 2614: 2588: 2513: 2388: 2269: 2207: 2085: 2047: 1848: 1739: 1639: 1513:for some scale factor 1505:, and the orthocenter 1480: 1392:orthocentroidal circle 1377: 1338: 1270:In Dörrie's book, the 1261: 1241: 1221: 1201: 1138: 904: 627: 523: 470: 443: 360: 332: 309: 286: 263: 144:and the center of the 74: 4205:Related constructions 4196: 4176: 4153: 4127: 4107: 4084: 4064: 4044: 4024: 4004: 3981: 3961: 3941: 3751:The Euler line of an 3731:The Euler line of an 3688:equilateral triangles 3674: 3626: 3430: 3354: 3199: 3197:{\displaystyle m_{E}} 3172: 3142: 3113: 3071: 3069:{\displaystyle t=-1.} 3042: 2920: 2894: 2763: 2737: 2615: 2589: 2514: 2389: 2270: 2208: 2086: 2048: 1893:trilinear coordinates 1849: 1740: 1640: 1481: 1390:is a diameter of the 1378: 1339: 1262: 1242: 1222: 1202: 1139: 905: 628: 524: 471: 444: 361: 333: 310: 287: 264: 22: 4742:(February 1, 2016), 4740:Stankova, Zvezdelina 4696:Bogomolny, Alexander 4468:Mathematical Gazette 4381:Mathematical Gazette 4185: 4165: 4136: 4116: 4096: 4073: 4053: 4033: 4013: 3993: 3970: 3950: 3930: 3921:circumcenter of mass 3840:convex quadrilateral 3767:Consider a triangle 3694:In special triangles 3642: 3447: 3364: 3211: 3181: 3151: 3121: 3092: 3051: 2935: 2918:{\displaystyle t=2.} 2903: 2778: 2761:{\displaystyle t=1.} 2746: 2630: 2613:{\displaystyle t=0.} 2598: 2545: 2401: 2279: 2229: 2098: 2063: 1902: 1752: 1655: 1546: 1408: 1349: 1310: 1299:and the orthocenter 1276:problem of Sylvester 1251: 1231: 1211: 1151: 920: 643: 540: 531:problem of Sylvester 480: 460: 373: 350: 322: 299: 276: 247: 224:center of similitude 116:determined from any 4643:Forum Geometricorum 4576:Forum Geometricorum 4552:Forum Geometricorum 4503:16, 2016, 257–267 . 4500:Forum Geometricorum 4484:Forum Geometricorum 4286:. Summarized at: 4151:{\displaystyle E=C} 3913:simplicial polytope 3907:Simplicial polytope 3901:twelve-point sphere 3815:orthocentric system 3753:automedian triangle 3747:Automedian triangle 3735:coincides with the 2929:de Longchamps point 262:{\displaystyle ABC} 216:tangential triangle 209:isosceles triangles 189:de Longchamps point 4762:Weisstein, Eric W. 4288:Dartmouth College. 4191: 4171: 4148: 4122: 4102: 4079: 4059: 4039: 4019: 3999: 3976: 3956: 3936: 3733:isosceles triangle 3727:Isosceles triangle 3669: 3621: 3425: 3349: 3194: 3167: 3137: 3108: 3066: 3037: 2915: 2889: 2758: 2732: 2610: 2584: 2524:linear combination 2509: 2384: 2265: 2203: 2081: 2043: 1844: 1797: 1735: 1635: 1588: 1476: 1373: 1334: 1257: 1237: 1217: 1197: 1134: 1085: 1083: 1027: 1025: 975: 973: 900: 895: 879: 877:(in triangle  810: 794: 792:(in triangle  725: 709: 707:(in triangle  623: 519: 466: 439: 356: 328: 305: 282: 259: 201:Gossard perspector 168:Individual centers 75: 58:(intersect at the 44:(intersect at the 4716:Kimberling, Clark 4194:{\displaystyle E} 4174:{\displaystyle P} 4125:{\displaystyle C} 4105:{\displaystyle P} 4082:{\displaystyle L} 4062:{\displaystyle L} 4042:{\displaystyle E} 4022:{\displaystyle L} 4002:{\displaystyle P} 3979:{\displaystyle P} 3959:{\displaystyle E} 3939:{\displaystyle P} 3889:three-dimensional 3852:quasicircumcenter 3823:nine-point center 3616: 2772:nine-point center 1796: 1587: 1260:{\displaystyle H} 1240:{\displaystyle G} 1220:{\displaystyle O} 1194: 1174: 1128: 1100: 1064: 1042: 1006: 990: 954: 943: 894: 878: 870: 850: 830: 809: 793: 785: 765: 745: 724: 708: 700: 680: 660: 617: 597: 577: 557: 517: 504: 491: 469:{\displaystyle G} 430: 410: 390: 359:{\displaystyle G} 331:{\displaystyle H} 308:{\displaystyle G} 285:{\displaystyle O} 182:nine-point center 148:of the triangle. 146:nine-point circle 33:nine-point circle 4796: 4775: 4774: 4756: 4726: 4724:Triangle Centers 4647: 4645:10, 2010: 55–77. 4638: 4632: 4630: 4613: 4591: 4585: 4583: 4573: 4564: 4558: 4548: 4542: 4540: 4524:(472): 151–154, 4513: 4507: 4495: 4489: 4480: 4471: 4464: 4458: 4447: 4438: 4435:College Geometry 4431: 4414: 4412: 4388:(522): 436–452, 4375: 4366: 4364: 4323: 4317: 4316: 4296: 4290: 4274: 4273:: 103–123. E325. 4255: 4249: 4248: 4236: 4200: 4198: 4197: 4192: 4180: 4178: 4177: 4172: 4157: 4155: 4154: 4149: 4131: 4129: 4128: 4123: 4111: 4109: 4108: 4103: 4088: 4086: 4085: 4080: 4068: 4066: 4065: 4060: 4048: 4046: 4045: 4040: 4028: 4026: 4025: 4020: 4008: 4006: 4005: 4000: 3985: 3983: 3982: 3977: 3965: 3963: 3962: 3957: 3945: 3943: 3942: 3937: 3737:axis of symmetry 3678: 3676: 3675: 3670: 3630: 3628: 3627: 3622: 3617: 3615: 3614: 3613: 3604: 3603: 3594: 3593: 3578: 3577: 3565: 3564: 3552: 3551: 3541: 3534: 3533: 3524: 3523: 3511: 3510: 3501: 3500: 3488: 3487: 3478: 3477: 3467: 3459: 3458: 3434: 3432: 3431: 3426: 3412: 3411: 3402: 3401: 3392: 3391: 3382: 3381: 3358: 3356: 3355: 3350: 3348: 3347: 3338: 3337: 3325: 3324: 3315: 3314: 3302: 3301: 3292: 3291: 3279: 3278: 3269: 3268: 3256: 3255: 3246: 3245: 3233: 3232: 3223: 3222: 3203: 3201: 3200: 3195: 3193: 3192: 3176: 3174: 3173: 3168: 3163: 3162: 3146: 3144: 3143: 3138: 3133: 3132: 3117: 3115: 3114: 3109: 3104: 3103: 3075: 3073: 3072: 3067: 3046: 3044: 3043: 3038: 2924: 2922: 2921: 2916: 2898: 2896: 2895: 2890: 2767: 2765: 2764: 2759: 2741: 2739: 2738: 2733: 2619: 2617: 2616: 2611: 2593: 2591: 2590: 2585: 2518: 2516: 2515: 2510: 2393: 2391: 2390: 2385: 2274: 2272: 2271: 2266: 2212: 2210: 2209: 2204: 2090: 2088: 2087: 2082: 2052: 2050: 2049: 2044: 1853: 1851: 1850: 1845: 1837: 1836: 1824: 1823: 1811: 1810: 1798: 1789: 1783: 1782: 1767: 1766: 1744: 1742: 1741: 1736: 1728: 1727: 1715: 1714: 1702: 1701: 1686: 1685: 1670: 1669: 1644: 1642: 1641: 1636: 1628: 1627: 1615: 1614: 1602: 1601: 1589: 1580: 1574: 1573: 1561: 1560: 1485: 1483: 1482: 1477: 1382: 1380: 1379: 1374: 1343: 1341: 1340: 1335: 1266: 1264: 1263: 1258: 1246: 1244: 1243: 1238: 1226: 1224: 1223: 1218: 1206: 1204: 1203: 1198: 1196: 1195: 1190: 1182: 1176: 1175: 1170: 1162: 1143: 1141: 1140: 1135: 1130: 1129: 1124: 1116: 1107: 1103: 1102: 1101: 1096: 1088: 1084: 1082: 1081: 1049: 1045: 1044: 1043: 1038: 1030: 1026: 1024: 1023: 997: 993: 992: 991: 986: 978: 974: 972: 971: 945: 944: 939: 931: 909: 907: 906: 901: 896: 892: 880: 876: 872: 871: 866: 858: 852: 851: 846: 838: 832: 831: 826: 818: 811: 807: 795: 791: 787: 786: 781: 773: 767: 766: 761: 753: 747: 746: 741: 733: 726: 722: 710: 706: 702: 701: 696: 688: 682: 681: 676: 668: 662: 661: 656: 648: 632: 630: 629: 624: 619: 618: 613: 605: 599: 598: 593: 585: 579: 578: 573: 565: 559: 558: 553: 545: 528: 526: 525: 520: 518: 510: 505: 497: 492: 484: 475: 473: 472: 467: 448: 446: 445: 440: 432: 431: 426: 418: 412: 411: 406: 398: 392: 391: 386: 378: 365: 363: 362: 357: 337: 335: 334: 329: 314: 312: 311: 306: 291: 289: 288: 283: 268: 266: 265: 260: 111: 110: 107: 106: 103: 100: 97: 67: 53: 39: 26: 4804: 4803: 4799: 4798: 4797: 4795: 4794: 4793: 4779: 4778: 4760: 4759: 4738: 4735:Wayback Machine 4714: 4656: 4651: 4650: 4639: 4635: 4593: 4592: 4588: 4571: 4566: 4565: 4561: 4549: 4545: 4530:10.2307/3620241 4515: 4514: 4510: 4496: 4492: 4481: 4474: 4465: 4461: 4448: 4441: 4432: 4417: 4377: 4376: 4369: 4325: 4324: 4320: 4313: 4298: 4297: 4293: 4259:Euler, Leonhard 4257: 4256: 4252: 4247:: i–xxv, 1–295. 4238: 4237: 4228: 4223: 4207: 4183: 4182: 4163: 4162: 4134: 4133: 4114: 4113: 4094: 4093: 4071: 4070: 4051: 4050: 4031: 4030: 4011: 4010: 3991: 3990: 3968: 3967: 3948: 3947: 3928: 3927: 3909: 3881: 3875: 3836: 3831: 3829:Generalizations 3801: 3794: 3787: 3780: 3765: 3749: 3729: 3701: 3696: 3684: 3640: 3639: 3638:if and only if 3605: 3595: 3585: 3569: 3556: 3543: 3542: 3525: 3515: 3502: 3492: 3479: 3469: 3468: 3450: 3445: 3444: 3403: 3393: 3383: 3373: 3362: 3361: 3339: 3329: 3316: 3306: 3293: 3283: 3270: 3260: 3247: 3237: 3224: 3214: 3209: 3208: 3184: 3179: 3178: 3154: 3149: 3148: 3124: 3119: 3118: 3095: 3090: 3089: 3082: 3049: 3048: 2933: 2932: 2931:has trilinears 2901: 2900: 2776: 2775: 2774:has trilinears 2744: 2743: 2628: 2627: 2626:has trilinears 2596: 2595: 2543: 2542: 2541:has trilinears 2399: 2398: 2277: 2276: 2227: 2226: 2219: 2096: 2095: 2061: 2060: 1900: 1899: 1865: 1860: 1828: 1815: 1802: 1774: 1758: 1750: 1749: 1719: 1706: 1693: 1677: 1661: 1653: 1652: 1619: 1606: 1593: 1565: 1552: 1544: 1543: 1406: 1405: 1347: 1346: 1308: 1307: 1289: 1284: 1249: 1248: 1229: 1228: 1209: 1208: 1183: 1163: 1149: 1148: 1147:In conclusion, 1117: 1089: 1063: 1059: 1031: 1005: 1001: 979: 953: 949: 932: 918: 917: 859: 839: 819: 774: 754: 734: 689: 669: 649: 641: 640: 606: 586: 566: 546: 538: 537: 529:. Further, the 478: 477: 458: 457: 419: 399: 379: 371: 370: 348: 347: 320: 319: 297: 296: 274: 273: 245: 244: 241: 236: 203:. However, the 193:Schiffler point 178:triangle center 170: 165: 94: 90: 73: 65: 63: 51: 49: 37: 35: 24: 17: 12: 11: 5: 4802: 4800: 4792: 4791: 4781: 4780: 4777: 4776: 4757: 4727: 4712: 4693: 4676: 4663: 4655: 4654:External links 4652: 4649: 4648: 4633: 4604:(4): 815–836, 4586: 4559: 4543: 4508: 4490: 4472: 4459: 4439: 4415: 4367: 4336:(1–2): 41–50, 4318: 4312:978-0883850992 4311: 4291: 4250: 4225: 4224: 4222: 4219: 4206: 4203: 4190: 4170: 4147: 4144: 4141: 4121: 4101: 4078: 4069:or a point on 4058: 4038: 4018: 3998: 3975: 3955: 3935: 3908: 3905: 3877:Main article: 3874: 3871: 3835: 3832: 3830: 3827: 3799: 3792: 3785: 3778: 3764: 3761: 3748: 3745: 3728: 3725: 3705:right triangle 3700: 3699:Right triangle 3697: 3695: 3692: 3683: 3680: 3668: 3665: 3662: 3659: 3656: 3653: 3650: 3647: 3632: 3631: 3620: 3612: 3608: 3602: 3598: 3592: 3588: 3584: 3581: 3576: 3572: 3568: 3563: 3559: 3555: 3550: 3546: 3540: 3537: 3532: 3528: 3522: 3518: 3514: 3509: 3505: 3499: 3495: 3491: 3486: 3482: 3476: 3472: 3465: 3462: 3457: 3453: 3438: 3437: 3436: 3435: 3424: 3421: 3418: 3415: 3410: 3406: 3400: 3396: 3390: 3386: 3380: 3376: 3372: 3369: 3346: 3342: 3336: 3332: 3328: 3323: 3319: 3313: 3309: 3305: 3300: 3296: 3290: 3286: 3282: 3277: 3273: 3267: 3263: 3259: 3254: 3250: 3244: 3240: 3236: 3231: 3227: 3221: 3217: 3191: 3187: 3166: 3161: 3157: 3136: 3131: 3127: 3107: 3102: 3098: 3081: 3078: 3077: 3076: 3065: 3062: 3059: 3056: 3036: 3033: 3030: 3027: 3024: 3021: 3018: 3015: 3012: 3009: 3006: 3003: 3000: 2997: 2994: 2991: 2988: 2985: 2982: 2979: 2976: 2973: 2970: 2967: 2964: 2961: 2958: 2955: 2952: 2949: 2946: 2943: 2940: 2925: 2914: 2911: 2908: 2888: 2885: 2882: 2879: 2876: 2873: 2870: 2867: 2864: 2861: 2858: 2855: 2852: 2849: 2846: 2843: 2840: 2837: 2834: 2831: 2828: 2825: 2822: 2819: 2816: 2813: 2810: 2807: 2804: 2801: 2798: 2795: 2792: 2789: 2786: 2783: 2768: 2757: 2754: 2751: 2731: 2728: 2725: 2722: 2719: 2716: 2713: 2710: 2707: 2704: 2701: 2698: 2695: 2692: 2689: 2686: 2683: 2680: 2677: 2674: 2671: 2668: 2665: 2662: 2659: 2656: 2653: 2650: 2647: 2644: 2641: 2638: 2635: 2620: 2609: 2606: 2603: 2583: 2580: 2577: 2574: 2571: 2568: 2565: 2562: 2559: 2556: 2553: 2550: 2520: 2519: 2508: 2505: 2502: 2499: 2496: 2493: 2490: 2487: 2484: 2481: 2478: 2475: 2472: 2469: 2466: 2463: 2460: 2457: 2454: 2451: 2448: 2445: 2442: 2439: 2436: 2433: 2430: 2427: 2424: 2421: 2418: 2415: 2412: 2409: 2406: 2383: 2380: 2377: 2374: 2371: 2368: 2365: 2362: 2359: 2356: 2353: 2350: 2347: 2344: 2341: 2338: 2335: 2332: 2329: 2326: 2323: 2320: 2317: 2314: 2311: 2308: 2305: 2302: 2299: 2296: 2293: 2290: 2287: 2284: 2264: 2261: 2258: 2255: 2252: 2249: 2246: 2243: 2240: 2237: 2234: 2218: 2215: 2214: 2213: 2202: 2199: 2196: 2193: 2190: 2187: 2184: 2181: 2178: 2175: 2172: 2169: 2166: 2163: 2160: 2157: 2154: 2151: 2148: 2145: 2142: 2139: 2136: 2133: 2130: 2127: 2124: 2121: 2118: 2115: 2112: 2109: 2106: 2103: 2080: 2077: 2074: 2071: 2068: 2054: 2053: 2042: 2039: 2036: 2033: 2030: 2027: 2024: 2021: 2018: 2015: 2012: 2009: 2006: 2003: 2000: 1997: 1994: 1991: 1988: 1985: 1982: 1979: 1976: 1973: 1970: 1967: 1964: 1961: 1958: 1955: 1952: 1949: 1946: 1943: 1940: 1937: 1934: 1931: 1928: 1925: 1922: 1919: 1916: 1913: 1910: 1907: 1864: 1861: 1859: 1858:Representation 1856: 1855: 1854: 1843: 1840: 1835: 1831: 1827: 1822: 1818: 1814: 1809: 1805: 1801: 1795: 1792: 1786: 1781: 1777: 1773: 1770: 1765: 1761: 1757: 1746: 1745: 1734: 1731: 1726: 1722: 1718: 1713: 1709: 1705: 1700: 1696: 1692: 1689: 1684: 1680: 1676: 1673: 1668: 1664: 1660: 1646: 1645: 1634: 1631: 1626: 1622: 1618: 1613: 1609: 1605: 1600: 1596: 1592: 1586: 1583: 1577: 1572: 1568: 1564: 1559: 1555: 1551: 1487: 1486: 1475: 1472: 1469: 1466: 1463: 1460: 1457: 1453: 1450: 1447: 1444: 1441: 1438: 1435: 1432: 1428: 1425: 1422: 1419: 1416: 1413: 1384: 1383: 1372: 1369: 1366: 1363: 1360: 1357: 1354: 1344: 1333: 1330: 1327: 1324: 1321: 1318: 1315: 1288: 1285: 1283: 1280: 1256: 1236: 1216: 1193: 1189: 1186: 1179: 1173: 1169: 1166: 1159: 1156: 1145: 1144: 1133: 1127: 1123: 1120: 1113: 1110: 1106: 1099: 1095: 1092: 1080: 1077: 1074: 1067: 1062: 1058: 1055: 1052: 1048: 1041: 1037: 1034: 1022: 1019: 1016: 1009: 1004: 1000: 996: 989: 985: 982: 970: 967: 964: 957: 952: 948: 942: 938: 935: 928: 925: 911: 910: 899: 889: 886: 883: 869: 865: 862: 855: 849: 845: 842: 835: 829: 825: 822: 814: 804: 801: 798: 784: 780: 777: 770: 764: 760: 757: 750: 744: 740: 737: 729: 719: 716: 713: 699: 695: 692: 685: 679: 675: 672: 665: 659: 655: 652: 634: 633: 622: 616: 612: 609: 602: 596: 592: 589: 582: 576: 572: 569: 562: 556: 552: 549: 516: 513: 508: 503: 500: 495: 490: 487: 465: 450: 449: 438: 435: 429: 425: 422: 415: 409: 405: 402: 395: 389: 385: 382: 355: 327: 304: 281: 258: 255: 252: 240: 239:A vector proof 237: 235: 232: 169: 166: 164: 161: 87:Leonhard Euler 85:, named after 64: 50: 36: 23: 15: 13: 10: 9: 6: 4: 3: 2: 4801: 4790: 4787: 4786: 4784: 4772: 4771: 4766: 4763: 4758: 4755: 4751: 4750: 4745: 4741: 4736: 4732: 4728: 4725: 4721: 4717: 4713: 4711: 4710: 4705: 4701: 4697: 4694: 4692: 4688: 4684: 4680: 4677: 4675: 4671: 4667: 4664: 4661: 4658: 4657: 4653: 4646: 4644: 4637: 4634: 4629: 4625: 4621: 4617: 4612: 4607: 4603: 4599: 4598: 4590: 4587: 4581: 4577: 4570: 4563: 4560: 4557: 4553: 4547: 4544: 4539: 4535: 4531: 4527: 4523: 4519: 4512: 4509: 4506: 4502: 4501: 4494: 4491: 4488: 4485: 4479: 4477: 4473: 4469: 4463: 4460: 4456: 4455:0-486-61348-8 4452: 4446: 4444: 4440: 4436: 4430: 4428: 4426: 4424: 4422: 4420: 4416: 4411: 4407: 4403: 4399: 4395: 4391: 4387: 4383: 4382: 4374: 4372: 4368: 4363: 4359: 4355: 4351: 4347: 4343: 4339: 4335: 4331: 4330: 4322: 4319: 4314: 4308: 4304: 4303: 4295: 4292: 4289: 4285: 4282: 4278: 4275:Reprinted in 4272: 4268: 4264: 4260: 4254: 4251: 4246: 4242: 4235: 4233: 4231: 4227: 4220: 4218: 4216: 4212: 4204: 4202: 4188: 4168: 4159: 4145: 4142: 4139: 4119: 4099: 4090: 4076: 4056: 4036: 4016: 3996: 3987: 3973: 3953: 3933: 3926:Suppose that 3924: 3922: 3918: 3914: 3906: 3904: 3902: 3898: 3894: 3890: 3886: 3880: 3872: 3870: 3868: 3864: 3860: 3856: 3853: 3849: 3845: 3841: 3834:Quadrilateral 3833: 3828: 3826: 3824: 3820: 3816: 3811: 3809: 3805: 3798: 3791: 3784: 3777: 3774: 3770: 3762: 3760: 3758: 3754: 3746: 3744: 3742: 3738: 3734: 3726: 3724: 3722: 3718: 3714: 3710: 3706: 3698: 3693: 3691: 3689: 3681: 3679: 3666: 3663: 3660: 3657: 3654: 3651: 3648: 3645: 3637: 3618: 3610: 3606: 3600: 3596: 3590: 3586: 3582: 3579: 3574: 3570: 3566: 3561: 3557: 3553: 3548: 3544: 3538: 3535: 3530: 3526: 3520: 3516: 3512: 3507: 3503: 3497: 3493: 3489: 3484: 3480: 3474: 3470: 3463: 3460: 3455: 3451: 3443: 3442: 3441: 3422: 3419: 3416: 3413: 3408: 3404: 3398: 3394: 3388: 3384: 3378: 3374: 3370: 3367: 3360: 3359: 3344: 3340: 3334: 3330: 3326: 3321: 3317: 3311: 3307: 3303: 3298: 3294: 3288: 3284: 3280: 3275: 3271: 3265: 3261: 3257: 3252: 3248: 3242: 3238: 3234: 3229: 3225: 3219: 3215: 3207: 3206: 3205: 3189: 3185: 3164: 3159: 3155: 3134: 3129: 3125: 3105: 3100: 3096: 3087: 3079: 3063: 3060: 3057: 3054: 3034: 3031: 3028: 3025: 3022: 3019: 3016: 3013: 3010: 3007: 3004: 3001: 2998: 2995: 2992: 2989: 2986: 2983: 2980: 2977: 2974: 2971: 2968: 2965: 2962: 2959: 2956: 2953: 2950: 2947: 2944: 2941: 2938: 2930: 2926: 2912: 2909: 2906: 2886: 2883: 2880: 2877: 2874: 2871: 2868: 2865: 2862: 2859: 2856: 2853: 2850: 2847: 2844: 2841: 2838: 2835: 2832: 2829: 2826: 2823: 2820: 2817: 2814: 2811: 2808: 2805: 2802: 2799: 2796: 2793: 2790: 2787: 2784: 2781: 2773: 2769: 2755: 2752: 2749: 2729: 2726: 2723: 2720: 2717: 2714: 2711: 2708: 2705: 2702: 2699: 2696: 2693: 2690: 2687: 2684: 2681: 2678: 2675: 2672: 2669: 2666: 2663: 2660: 2657: 2654: 2651: 2648: 2645: 2642: 2639: 2636: 2633: 2625: 2621: 2607: 2604: 2601: 2581: 2578: 2575: 2572: 2569: 2566: 2563: 2560: 2557: 2554: 2551: 2548: 2540: 2536: 2535: 2534: 2533:For example: 2531: 2529: 2525: 2506: 2503: 2500: 2497: 2494: 2491: 2488: 2485: 2482: 2479: 2476: 2473: 2470: 2467: 2464: 2461: 2458: 2455: 2452: 2449: 2446: 2443: 2440: 2437: 2434: 2431: 2428: 2425: 2422: 2419: 2416: 2413: 2410: 2407: 2404: 2397: 2396: 2395: 2381: 2375: 2372: 2369: 2366: 2363: 2360: 2357: 2354: 2351: 2348: 2345: 2342: 2339: 2336: 2333: 2330: 2327: 2324: 2321: 2318: 2315: 2312: 2309: 2306: 2303: 2300: 2297: 2294: 2291: 2288: 2285: 2282: 2262: 2259: 2256: 2253: 2250: 2247: 2244: 2241: 2238: 2235: 2232: 2224: 2216: 2200: 2197: 2194: 2188: 2185: 2182: 2179: 2176: 2173: 2170: 2164: 2161: 2155: 2152: 2149: 2146: 2143: 2140: 2137: 2131: 2128: 2122: 2119: 2116: 2113: 2110: 2107: 2104: 2094: 2093: 2092: 2078: 2075: 2072: 2069: 2066: 2059: 2040: 2037: 2034: 2028: 2025: 2022: 2016: 2013: 2007: 2004: 1998: 1995: 1992: 1989: 1983: 1980: 1977: 1971: 1968: 1962: 1959: 1953: 1950: 1947: 1944: 1938: 1935: 1932: 1926: 1923: 1917: 1914: 1908: 1905: 1898: 1897: 1896: 1894: 1890: 1886: 1882: 1878: 1874: 1870: 1862: 1857: 1841: 1833: 1829: 1825: 1820: 1816: 1812: 1807: 1803: 1793: 1790: 1784: 1779: 1775: 1771: 1768: 1763: 1759: 1755: 1748: 1747: 1732: 1724: 1720: 1716: 1711: 1707: 1703: 1698: 1694: 1687: 1682: 1678: 1674: 1671: 1666: 1662: 1658: 1651: 1650: 1649: 1648:In addition, 1632: 1624: 1620: 1616: 1611: 1607: 1603: 1598: 1594: 1584: 1581: 1575: 1570: 1566: 1562: 1557: 1553: 1549: 1542: 1541: 1540: 1538: 1534: 1530: 1526: 1523: 1518: 1516: 1512: 1508: 1504: 1500: 1496: 1492: 1473: 1470: 1467: 1464: 1461: 1458: 1455: 1451: 1448: 1445: 1442: 1439: 1436: 1433: 1430: 1426: 1423: 1420: 1417: 1414: 1411: 1404: 1403: 1402: 1400: 1395: 1393: 1389: 1370: 1367: 1364: 1361: 1358: 1355: 1352: 1345: 1331: 1328: 1325: 1322: 1319: 1316: 1313: 1306: 1305: 1304: 1302: 1298: 1294: 1286: 1281: 1279: 1277: 1273: 1268: 1254: 1234: 1214: 1187: 1184: 1177: 1167: 1164: 1157: 1154: 1131: 1121: 1118: 1111: 1108: 1104: 1093: 1090: 1060: 1056: 1053: 1050: 1046: 1035: 1032: 1002: 998: 994: 983: 980: 950: 946: 936: 933: 926: 923: 916: 915: 914: 897: 887: 884: 881: 863: 860: 853: 843: 840: 833: 823: 820: 812: 802: 799: 796: 778: 775: 768: 758: 755: 748: 738: 735: 727: 717: 714: 711: 693: 690: 683: 673: 670: 663: 653: 650: 639: 638: 637: 620: 610: 607: 600: 590: 587: 580: 570: 567: 560: 550: 547: 536: 535: 534: 532: 514: 511: 506: 501: 498: 493: 488: 485: 463: 455: 436: 433: 423: 420: 413: 403: 400: 393: 383: 380: 369: 368: 367: 353: 345: 341: 325: 318: 302: 295: 279: 272: 256: 253: 250: 238: 233: 231: 229: 225: 221: 217: 212: 210: 206: 202: 198: 194: 190: 185: 183: 179: 175: 167: 162: 160: 158: 154: 153:quadrilateral 149: 147: 143: 139: 135: 131: 127: 123: 119: 115: 109: 88: 84: 80: 71: 61: 57: 47: 43: 34: 30: 21: 4768: 4765:"Euler Line" 4747: 4731:Ghostarchive 4729:Archived at 4723: 4709:Cut-the-Knot 4707: 4666:"Euler Line" 4642: 4636: 4601: 4595: 4589: 4579: 4575: 4562: 4551: 4546: 4521: 4517: 4511: 4498: 4493: 4483: 4467: 4462: 4434: 4385: 4379: 4361: 4333: 4327: 4321: 4301: 4294: 4276: 4270: 4266: 4253: 4244: 4240: 4208: 4160: 4091: 3988: 3925: 3910: 3882: 3866: 3862: 3854: 3847: 3843: 3837: 3812: 3807: 3796: 3789: 3782: 3775: 3768: 3766: 3750: 3730: 3702: 3685: 3635: 3633: 3439: 3083: 2539:circumcenter 2532: 2527: 2522:formed as a 2521: 2222: 2220: 2055: 1888: 1884: 1880: 1876: 1872: 1868: 1866: 1647: 1536: 1532: 1528: 1524: 1522:circumradius 1519: 1514: 1510: 1506: 1502: 1498: 1494: 1490: 1488: 1398: 1396: 1387: 1386:The segment 1385: 1300: 1296: 1292: 1290: 1271: 1269: 1146: 912: 635: 451: 344:free vectors 339: 271:circumcenter 242: 220:circumcircle 213: 197:Exeter point 186: 171: 150: 142:Exeter point 134:circumcenter 126:central line 120:that is not 82: 76: 70:circumcenter 4749:Numberphile 4277:Opera Omnia 3897:Monge point 3885:tetrahedron 3873:Tetrahedron 3819:orthocenter 3755:(one whose 1397:The center 317:orthocenter 157:tetrahedron 130:orthocenter 122:equilateral 60:orthocenter 4221:References 4049:is either 3850:, and the 3804:concurrent 3790:A, B, C, F 3713:hypotenuse 1282:Properties 1272:Euler line 342:relies on 199:, and the 124:. It is a 83:Euler line 29:the center 4770:MathWorld 4611:1301.0496 4582:: 289–295 4410:125341434 4358:121434528 4215:directrix 3917:simplices 3859:collinear 3717:altitudes 3658:⁡ 3649:⁡ 3464:− 3061:− 3029:⁡ 3020:⁡ 3014:− 3008:⁡ 2996:⁡ 2987:⁡ 2981:− 2975:⁡ 2963:⁡ 2954:⁡ 2948:− 2942:⁡ 2881:⁡ 2872:⁡ 2857:⁡ 2845:⁡ 2836:⁡ 2821:⁡ 2809:⁡ 2800:⁡ 2785:⁡ 2724:⁡ 2715:⁡ 2703:⁡ 2691:⁡ 2682:⁡ 2670:⁡ 2658:⁡ 2649:⁡ 2637:⁡ 2576:⁡ 2564:⁡ 2552:⁡ 2504:⁡ 2495:⁡ 2480:⁡ 2468:⁡ 2459:⁡ 2444:⁡ 2432:⁡ 2423:⁡ 2408:⁡ 2373:⁡ 2364:⁡ 2352:⁡ 2343:⁡ 2331:⁡ 2322:⁡ 2310:⁡ 2298:⁡ 2286:⁡ 2260:⁡ 2248:⁡ 2236:⁡ 2195:γ 2186:⁡ 2180:− 2174:⁡ 2162:β 2153:⁡ 2147:− 2141:⁡ 2129:α 2120:⁡ 2114:− 2108:⁡ 2079:γ 2073:β 2067:α 2026:− 2017:⁡ 1999:⁡ 1981:− 1972:⁡ 1954:⁡ 1936:− 1927:⁡ 1909:⁡ 1785:− 1688:− 1576:− 1443:⋅ 1192:→ 1172:→ 1158:⋅ 1126:→ 1112:− 1098:→ 1066:∑ 1057:− 1040:→ 1008:∑ 988:→ 956:∑ 941:→ 927:⋅ 868:→ 848:→ 828:→ 783:→ 763:→ 743:→ 698:→ 678:→ 658:→ 615:→ 595:→ 575:→ 555:→ 533:reads as 428:→ 408:→ 388:→ 340:collinear 174:collinear 56:Altitudes 4783:Category 4733:and the 4628:12307207 4402:40378417 4261:(1767). 4211:extended 3741:incenter 2624:centroid 1887: : 1883: : 1863:Equation 1274:and the 315:and the 294:centroid 205:incenter 155:and the 138:centroid 118:triangle 112:), is a 79:geometry 46:centroid 4754:YouTube 4702:" and " 4672:at the 4538:3620241 4350:2430410 4284:0061061 4132:, then 4029:, then 3757:medians 3711:to the 226:of the 42:Medians 31:of the 4685:, and 4626:  4536:  4453:  4408:  4400:  4356:  4348:  4309:  4092:2. If 3989:1. If 3709:median 1535:, and 292:, the 234:Proofs 228:orthic 195:, the 191:, the 180:, the 140:, the 136:, the 132:, the 81:, the 66:  54:  52:  40:  38:  25:  4624:S2CID 4606:arXiv 4572:(PDF) 4534:JSTOR 4406:S2CID 4398:JSTOR 4354:S2CID 3893:faces 3887:is a 3838:In a 3771:with 3703:In a 3084:In a 3080:Slope 4668:and 4451:ISBN 4307:ISBN 3857:are 3802:are 3795:and 3781:and 3147:and 2927:The 2770:The 2622:The 2537:The 1867:Let 1509:at 6 1497:at 2 1247:and 476:are 338:are 243:Let 214:The 114:line 4706:", 4698:, " 4689:at 4616:doi 4526:doi 4390:doi 4338:doi 4245:129 3865:= 2 3808:ABC 3769:ABC 3655:tan 3646:tan 3026:cos 3017:cos 3005:cos 2993:cos 2984:cos 2972:cos 2960:cos 2951:cos 2939:cos 2878:cos 2869:cos 2854:cos 2842:cos 2833:cos 2818:cos 2806:cos 2797:cos 2782:cos 2721:cos 2712:cos 2700:cos 2688:cos 2679:cos 2667:cos 2655:cos 2646:cos 2634:cos 2573:cos 2561:cos 2549:cos 2501:cos 2492:cos 2477:cos 2465:cos 2456:cos 2441:cos 2429:cos 2420:cos 2405:cos 2370:cos 2361:cos 2349:cos 2340:cos 2328:cos 2319:cos 2307:sec 2295:sec 2283:sec 2257:cos 2245:cos 2233:cos 2183:tan 2171:tan 2150:tan 2138:tan 2117:tan 2105:tan 2091:is 2014:sin 1996:sin 1969:sin 1951:sin 1924:sin 1906:sin 456:of 77:In 4785:: 4767:. 4752:, 4746:, 4737:: 4722:, 4718:, 4681:, 4622:, 4614:, 4602:51 4600:, 4578:, 4574:, 4532:, 4522:75 4520:, 4475:^ 4442:^ 4418:^ 4404:, 4396:, 4386:91 4384:, 4370:^ 4360:, 4352:, 4346:MR 4344:, 4334:52 4332:, 4281:MR 4271:11 4269:. 4243:. 4229:^ 4217:. 4158:. 4089:. 3911:A 3883:A 3869:. 3867:GO 3863:HG 3810:. 3667:3. 3636:BC 3423:0. 3064:1. 2913:2. 2756:1. 2608:0. 2530:. 2201:0. 2041:0. 1875:, 1871:, 1539:: 1531:, 1517:. 1394:. 1388:GH 1227:, 437:0. 159:. 105:ər 99:ɔɪ 4773:. 4662:. 4631:. 4618:: 4608:: 4584:. 4580:6 4541:. 4528:: 4413:. 4392:: 4365:. 4340:: 4315:. 4189:E 4169:P 4146:C 4143:= 4140:E 4120:C 4100:P 4077:L 4057:L 4037:E 4017:L 3997:P 3974:P 3954:E 3934:P 3855:O 3848:G 3844:H 3800:2 3797:F 3793:1 3786:2 3783:F 3779:1 3776:F 3664:= 3661:C 3652:B 3619:. 3611:3 3607:m 3601:2 3597:m 3591:1 3587:m 3583:3 3580:+ 3575:3 3571:m 3567:+ 3562:2 3558:m 3554:+ 3549:1 3545:m 3539:3 3536:+ 3531:3 3527:m 3521:2 3517:m 3513:+ 3508:3 3504:m 3498:1 3494:m 3490:+ 3485:2 3481:m 3475:1 3471:m 3461:= 3456:E 3452:m 3420:= 3417:3 3414:+ 3409:E 3405:m 3399:3 3395:m 3389:2 3385:m 3379:1 3375:m 3371:3 3368:+ 3345:E 3341:m 3335:3 3331:m 3327:+ 3322:E 3318:m 3312:2 3308:m 3304:+ 3299:3 3295:m 3289:2 3285:m 3281:+ 3276:E 3272:m 3266:1 3262:m 3258:+ 3253:3 3249:m 3243:1 3239:m 3235:+ 3230:2 3226:m 3220:1 3216:m 3190:E 3186:m 3165:, 3160:3 3156:m 3135:, 3130:2 3126:m 3106:, 3101:1 3097:m 3058:= 3055:t 3035:, 3032:B 3023:A 3011:C 3002:: 2999:A 2990:C 2978:B 2969:: 2966:C 2957:B 2945:A 2910:= 2907:t 2887:, 2884:B 2875:A 2866:2 2863:+ 2860:C 2851:: 2848:A 2839:C 2830:2 2827:+ 2824:B 2815:: 2812:C 2803:B 2794:2 2791:+ 2788:A 2753:= 2750:t 2730:, 2727:B 2718:A 2709:+ 2706:C 2697:: 2694:A 2685:C 2676:+ 2673:B 2664:: 2661:C 2652:B 2643:+ 2640:A 2605:= 2602:t 2582:, 2579:C 2570:: 2567:B 2558:: 2555:A 2528:t 2507:B 2498:A 2489:t 2486:+ 2483:C 2474:: 2471:A 2462:C 2453:t 2450:+ 2447:B 2438:: 2435:C 2426:B 2417:t 2414:+ 2411:A 2382:, 2379:) 2376:B 2367:A 2358:: 2355:A 2346:C 2337:: 2334:C 2325:B 2316:= 2313:C 2304:: 2301:B 2292:: 2289:A 2263:C 2254:: 2251:B 2242:: 2239:A 2223:t 2198:= 2192:) 2189:A 2177:B 2168:( 2165:+ 2159:) 2156:C 2144:A 2135:( 2132:+ 2126:) 2123:B 2111:C 2102:( 2076:: 2070:: 2038:= 2035:z 2032:) 2029:B 2023:A 2020:( 2011:) 2008:C 2005:2 2002:( 1993:+ 1990:y 1987:) 1984:A 1978:C 1975:( 1966:) 1963:B 1960:2 1957:( 1948:+ 1945:x 1942:) 1939:C 1933:B 1930:( 1921:) 1918:A 1915:2 1912:( 1889:z 1885:y 1881:x 1877:C 1873:B 1869:A 1842:. 1839:) 1834:2 1830:c 1826:+ 1821:2 1817:b 1813:+ 1808:2 1804:a 1800:( 1794:9 1791:4 1780:2 1776:R 1772:4 1769:= 1764:2 1760:H 1756:G 1733:; 1730:) 1725:2 1721:c 1717:+ 1712:2 1708:b 1704:+ 1699:2 1695:a 1691:( 1683:2 1679:R 1675:9 1672:= 1667:2 1663:H 1659:O 1633:. 1630:) 1625:2 1621:c 1617:+ 1612:2 1608:b 1604:+ 1599:2 1595:a 1591:( 1585:9 1582:1 1571:2 1567:R 1563:= 1558:2 1554:O 1550:G 1537:c 1533:b 1529:a 1525:R 1515:t 1511:t 1507:H 1503:t 1499:t 1495:G 1491:O 1474:. 1471:N 1468:G 1465:3 1462:= 1459:H 1456:N 1452:, 1449:N 1446:G 1440:2 1437:= 1434:G 1431:O 1427:, 1424:H 1421:N 1418:= 1415:N 1412:O 1399:N 1371:. 1368:O 1365:G 1362:3 1359:= 1356:H 1353:O 1332:; 1329:O 1326:G 1323:2 1320:= 1317:H 1314:G 1301:H 1297:O 1293:G 1255:H 1235:G 1215:O 1188:H 1185:O 1178:= 1168:G 1165:O 1155:3 1132:. 1122:H 1119:O 1109:= 1105:) 1094:A 1091:O 1079:c 1076:y 1073:c 1061:( 1054:0 1051:= 1047:) 1036:O 1033:A 1021:c 1018:y 1015:c 1003:( 999:+ 995:) 984:A 981:G 969:c 966:y 963:c 951:( 947:= 937:O 934:G 924:3 898:. 893:) 888:O 885:G 882:C 864:O 861:C 854:+ 844:C 841:G 834:= 824:O 821:G 813:, 808:) 803:O 800:G 797:B 779:O 776:B 769:+ 759:B 756:G 749:= 739:O 736:G 728:, 723:) 718:O 715:G 712:A 694:O 691:A 684:+ 674:A 671:G 664:= 654:O 651:G 621:. 611:C 608:O 601:+ 591:B 588:O 581:+ 571:A 568:O 561:= 551:H 548:O 515:3 512:1 507:: 502:3 499:1 494:: 489:3 486:1 464:G 434:= 424:C 421:G 414:+ 404:B 401:G 394:+ 384:A 381:G 354:G 326:H 303:G 280:O 257:C 254:B 251:A 108:/ 102:l 96:ˈ 93:/ 89:( 72:) 62:) 48:)

Index


the center
nine-point circle
Medians
centroid
Altitudes
orthocenter
circumcenter
geometry
Leonhard Euler
/ˈɔɪlər/
line
triangle
equilateral
central line
orthocenter
circumcenter
centroid
Exeter point
nine-point circle
quadrilateral
tetrahedron
collinear
triangle center
nine-point center
de Longchamps point
Schiffler point
Exeter point
Gossard perspector
incenter

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