Legendre, A. M. (Adrien Marie), 1752-1833, Brewster, David, Sir, 1781-1868, Davies, Charles, 1798-1876 · New York, Wiley & Long · leaf 280
f the equal sides,and half this side, form a right-angled triangle, in which thereare known, the base, which is half the equal side of the poly-gon, and the angle at the vertex. Hence, the perpendicularcan be determined. Î. To find the area of a regular hexa-gon, whose sides are 20 feet each.… … CD 17.3205 1.238561 Perimeter =120, and half the perimeter =60.Then, 60 x 17.3205=1039.23, the area. 2. What is the area of an octagon whose side is 20 ? Ans. 1931.36886. Remark II.—The area of a regular polygon of any numberof sides is easily calculated by the above rule. Let the areasof the…
Trigonometry · Geometry
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![An illustration from Divina proportione : opera a tutti glingegni perspicaci e curiosi necessaria oue ciascun studioso di philosophia: prospettiua pictura sculptura: architectura: musica: e altre mathematice: suavissima: sotile: e admirabile doctrina consequira: e delecterassi: co[n] varie questione de secretissima scientia (1509)](https://img.insideoutlibrary.com/img/200/ia-divinaproportion00paci-94-179.webp)
![An illustration from Cosmographia in qvatvor libros distribvta summo ordine, miraqve facilitate, ac breuitate ad magnam Ptolemæi mathematicam constructionem, ad vniuersamque astrologiam institutens. Francisco Barocio ... avtore. Cum præfatione eiusdem autoris, in qua perfecta quidem astrologiæ diuisio, & enarratio autorum illustrium, & voluminum ab eis conscriptorum in singulis astrologiæ partibus habetur: Joannis de Sacrobosco verò 84 errores, et alij permulti suorum expositorum, & sectatorum ostenduntur. rationibusq[uam] redarguuntur. Præcesserunt etiam quædam communia mathematica, necnon arithmetica, & geometrica principia, nonnullæq[uam] propositiones, de quibus in toto opere sæpe fit mentio: ac demum locupletissimus index eorum, quæ ipsa Cosmographia continentur .. (1585)](https://img.insideoutlibrary.com/img/200/ia-cosmographiainqv00baro-107-29.webp)
