Elements of geometry : containing the first six books of Euclid, with a supplement on the quadrature of the circle, and the geometry of solids : to which are added, Elements of plane and spherical geometry (1826)
Playfair, John, 1748-1819, Euclid · Philadelphia : Marot & Walter · leaf 218
PLANE TRIGONOMETRY. 2i: tHe angle C (def. 7.), and the triangles CGE, CBA being equiangular,CA : CB : : CE : CGf,that is, CA : CB : : R : sec. C. Cor. 2. If the analogies in this proposition, and in the above eo-rollary be arithmetically expressed, making the radius==l, they give sin. C= AH; tan.… … because B is the complement of C, cos. B ACreason, cos. C= yrp- Cor. 3. In every triangle, if a perpendicular be drawn, from anyof the angles on the opposite side, the seg-ments of that side are to one another asthe tangents of the parts into which theopposite angle is divided by the…
Euclid's Elements · Geometry · Trigonometry
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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-85-120.webp)
