Elements of geometry and trigonometry. Revised and adapted to the course of mathematical instruction in the United States (1856)
Legendre, A. M. (Adrien Marie), 1752-1833, Davies, Charles, 1798-1876 · New York : A.S. Barnes · leaf 237
fiorijeach angle in one of iJie triangles, tvill he measured hy asemicircumference, minus tlie side lying opptosite to it in thtother triangle. For, produce the sidesAB, AC, if necessary, tillthey meet EF, in G and //.The point A being the poleof the arc GH, the angleA is measured by that arc(p.… … BOOK IX. 233 Bures the angle A, is equal to a semicircumference mmiisthe side UF. In like manner, the angle B is measured byi circ- DF: the angle C, by \circ-DE, This property is reciprocal in the two triangles, sinceeach of tlieni is described in a similar manner by meansof the other. Thus the…
Geometry · Trigonometry
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