Page:Delambre - Histoire de l'astronomie moderne, tome 1, 1821.djvu/419

KEPLER. 333 sin AP = Vr — i Vh 2sin ± AP Octaèdre. n = 8, « = 3, m = 4; /i8o° cos ( J „ a « / cos 6o° sin 3o° i cos Am = — = — — — a . — «/. sin (— ) sin45 ° sin 450 n sin a Am = Am = 45°, lang A/?z = 1 , zAm = AB = 90% corde AB = 2sin Am = = v/f = l/a = arête 5 c’est la formule d’Euclide. h = cos AP = cot ~) cot (■—) = cot6o e cot45° = tang3o° = v / I> sin AP = v/f, lang AP s=j^5, 1 A = | ^| = ^ rayon du cercle circonscrit = sin AP = / , 1 — cos AP =3 asin 1 AP = 1 — /, sin 2 j AP ==| — V> sin i AP = s/TZTÇVl, 2sin i AP = 2^ — r V 7 ^ 2sin £ AP =a Y^ — 2V 7| = y/a 1 — v^i, cos 3 AP e= Vf+IT 7 !^ lang l AP = y /SES = y/oZZETEES facette = p sin 2 Am cot 6o° = 3 . £ . tang 3o = | ^ = = y/f == sm 60’, surf.pol_yèdre= 8y/| = /«±p = v/48, solidité = f A t/48 = v^ïf = v/^ = |, , T cos 45 l/| ._ sin { I = — g- = -,’=1/11/!= i/i, a sin 60 j/i V * V 3 V a » cas = t/f, cot ; 1 = v/i, sin I = 2S in ± 1 cos £ I = 2 y^a = 2 y/f = /f , cos I = — y’I, tang I = —