Knowledge

Talk:Ptolemy's table of chords

Source 📝

84: 74: 53: 189: 179: 158: 294: 273: 382: 22: 304: 585:
The problem with the comments above is that the arc and the chord are measured in different units: the arc in degrees, i.e. 180ths of the semicircle, and the chord in 120ths of the diameter. If the arc length were 60 times the number of radians, then the comments above would be unproblematic.
545:
The article currently states "For tiny arcs, the chord is to the arc as π is to 3, or more precisely, the ratio can be made as close as desired to π/3 ≈ 1.04719755 by making θ small enough. Thus, for the arc of (1/2)°, the chord is slightly more than the arc."
220: 140: 647: 458:
More on the geometric theorems: Their precise statements, how they are proved, how they are used in deriving trigonometric identities, how those identities are used in computing chords.
504:
Most, or maybe all, of the assertions are in the listed references, but I'd have to sort out which is which. I'll probably get to that in the coming weeks if no one beats me to it.
627: 255: 245: 356: 632: 622: 215: 557:
as π is to 3, or more precisely, the ratio can be made as close as desired to π/3 ≈ 1.04719755 by making θ small enough. Thus, for the arc of (1/2)°, the
642: 617: 346: 130: 652: 612: 211: 202: 163: 637: 106: 553:
longer than chord since in Euclidean Geometry the shortest path between two points is a straight line. It should state: For tiny arcs, the
568: 97: 58: 526:
The details of the description of the meaning of the "sixtieths" column doesn't seem to make a lot of sense. How is it scaled? --
317: 278: 33: 210:
content on Knowledge. If you would like to participate, you can edit the article attached to this page, or visit the
207: 492:
I found a cite for "an earlier table of chords by Hipparchus gave chords only for arcs that were multiples of 7½°)"
390: 435:
It was the earliest trigonometric table extensive enough for many practical purposes, including those of astronomy
194: 21: 591: 572: 509: 496: 39: 83: 564: 386: 105:
on Knowledge. If you would like to participate, please visit the project page, where you can join
587: 505: 89: 439:(an earlier table of chords by Hipparchus gave chords only for arcs that were multiples of 7½°). 73: 52: 531: 493: 309: 595: 576: 535: 513: 499: 178: 157: 606: 443:
Several centuries passed before more extensive trigonometric tables were created.
527: 102: 299: 184: 79: 322: 293: 272: 464:
When did more extensive tables supersede this one? Which century?
449:
The parts about the three distinct methods of computing chords.
372: 15: 549:
This statement has the arc and chord reversed. The arc is
461:
History of editions of the book including those in Arabic.
214:, where you can join the project and/or contribute to the 414: 408: 402: 396: 101:, a collaborative effort to improve the coverage of 648:Start-Class Astronomy articles of Low-importance 221:History of Science Collaboration of the Month 8: 321:, which collaborates on articles related to 19: 628:Low-importance history of science articles 267: 152: 47: 206:, an attempt to improve and organize the 230:Knowledge:WikiProject History of Science 633:WikiProject History of Science articles 623:Start-Class history of science articles 467:How did the table influence later work? 446:Page numbers in Glowatzki and Göttsche? 269: 233:Template:WikiProject History of Science 154: 49: 7: 428:Further inline citations, including: 315:This article is within the scope of 95:This article is within the scope of 559:chord is slightly less than the arc 38:It is of interest to the following 476:And probably other things......... 14: 643:Low-importance Astronomy articles 618:Low-priority mathematics articles 115:Knowledge:WikiProject Mathematics 653:Knowledge pages with to-do lists 613:Start-Class mathematics articles 380: 302: 292: 271: 187: 177: 156: 118:Template:WikiProject Mathematics 82: 72: 51: 20: 351:This article has been rated as 331:Knowledge:WikiProject Astronomy 250:This article has been rated as 135:This article has been rated as 638:Start-Class Astronomy articles 334:Template:WikiProject Astronomy 218:. You can also help with the 203:History of Science WikiProject 1: 109:and see a list of open tasks. 200:This article is part of the 236:history of science articles 669: 514:02:36, 12 March 2011 (UTC) 500:02:15, 12 March 2011 (UTC) 357:project's importance scale 256:project's importance scale 391:Ptolemy's table of chords 350: 287: 249: 195:History of science portal 172: 134: 67: 46: 596:18:21, 4 June 2019 (UTC) 577:11:00, 20 May 2014 (UTC) 536:21:14, 7 July 2013 (UTC) 141:project's priority scale 98:WikiProject Mathematics 28:This article is rated 318:WikiProject Astronomy 121:mathematics articles 555:arc is to the chord 420:Updated 2011-11-03 337:Astronomy articles 227:History of Science 208:history of science 164:History of Science 90:Mathematics portal 34:content assessment 567:comment added by 484: 483: 371: 370: 367: 366: 363: 362: 266: 265: 262: 261: 151: 150: 147: 146: 660: 579: 421: 384: 383: 373: 339: 338: 335: 332: 329: 312: 310:Astronomy portal 307: 306: 305: 296: 289: 288: 283: 275: 268: 238: 237: 234: 231: 228: 197: 192: 191: 190: 181: 174: 173: 168: 160: 153: 123: 122: 119: 116: 113: 92: 87: 86: 76: 69: 68: 63: 55: 48: 31: 25: 24: 16: 668: 667: 663: 662: 661: 659: 658: 657: 603: 602: 562: 543: 524: 489: 480: 479: 395: 381: 336: 333: 330: 327: 326: 308: 303: 301: 281: 235: 232: 229: 226: 225: 193: 188: 186: 166: 120: 117: 114: 111: 110: 88: 81: 61: 32:on Knowledge's 29: 12: 11: 5: 666: 664: 656: 655: 650: 645: 640: 635: 630: 625: 620: 615: 605: 604: 601: 600: 599: 598: 542: 539: 523: 520: 519: 518: 517: 516: 488: 485: 482: 481: 478: 477: 473: 472: 469: 468: 465: 462: 459: 455: 454: 452: 451: 450: 447: 444: 441: 436: 430: 429: 423: 378: 376: 369: 368: 365: 364: 361: 360: 353:Low-importance 349: 343: 342: 340: 314: 313: 297: 285: 284: 282:Low‑importance 276: 264: 263: 260: 259: 252:Low-importance 248: 242: 241: 239: 199: 198: 182: 170: 169: 167:Low‑importance 161: 149: 148: 145: 144: 133: 127: 126: 124: 107:the discussion 94: 93: 77: 65: 64: 56: 44: 43: 37: 26: 13: 10: 9: 6: 4: 3: 2: 665: 654: 651: 649: 646: 644: 641: 639: 636: 634: 631: 629: 626: 624: 621: 619: 616: 614: 611: 610: 608: 597: 593: 589: 588:Michael Hardy 584: 583: 582: 581: 580: 578: 574: 570: 566: 560: 556: 552: 547: 541:Arc vs. Chord 540: 538: 537: 533: 529: 521: 515: 511: 507: 506:Michael Hardy 503: 502: 501: 498: 495: 491: 490: 486: 475: 474: 471: 470: 466: 463: 460: 457: 456: 453: 448: 445: 442: 440: 437: 434: 433: 432: 431: 427: 426: 425: 422: 419: 416: 413: 410: 407: 404: 401: 398: 394: 392: 388: 377: 375: 374: 358: 354: 348: 345: 344: 341: 325:on Knowledge. 324: 320: 319: 311: 300: 298: 295: 291: 290: 286: 280: 277: 274: 270: 257: 253: 247: 244: 243: 240: 223: 222: 217: 213: 209: 205: 204: 196: 185: 183: 180: 176: 175: 171: 165: 162: 159: 155: 142: 138: 132: 129: 128: 125: 108: 104: 100: 99: 91: 85: 80: 78: 75: 71: 70: 66: 60: 57: 54: 50: 45: 41: 35: 27: 23: 18: 17: 569:212.21.46.23 563:— Preceding 558: 554: 550: 548: 544: 525: 438: 424: 417: 411: 405: 399: 385: 379: 352: 316: 251: 219: 212:project page 201: 137:Low-priority 136: 96: 62:Low‑priority 40:WikiProjects 494:Paul August 112:Mathematics 103:mathematics 59:Mathematics 30:Start-class 607:Categories 387:To-do list 216:discussion 522:Sixtieths 328:Astronomy 323:Astronomy 279:Astronomy 565:unsigned 487:Untitled 415:refresh 403:history 355:on the 254:on the 139:on the 551:always 528:Dfeuer 36:scale. 409:watch 592:talk 573:talk 532:talk 510:talk 397:edit 389:for 561:. 347:Low 246:Low 131:Low 609:: 594:) 575:) 534:) 512:) 590:( 571:( 530:( 508:( 497:☎ 418:· 412:· 406:· 400:· 393:: 359:. 258:. 224:. 143:. 42::

Index


content assessment
WikiProjects
WikiProject icon
Mathematics
WikiProject icon
icon
Mathematics portal
WikiProject Mathematics
mathematics
the discussion
Low
project's priority scale
WikiProject icon
History of Science
WikiProject icon
History of science portal
History of Science WikiProject
history of science
project page
discussion
History of Science Collaboration of the Month
Low
project's importance scale
WikiProject icon
Astronomy
WikiProject icon
Astronomy portal
WikiProject Astronomy
Astronomy

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