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 215
t A, one extremity of thearch AC, and meeting the diameter BC, which passes tlirough Cthe other extremity, is called the Tangent of the arch AC, or of theangle ABC. Cor. The tangent of half a right angle is equal to the radius. VII. The straight line BE, between the centre and the extremity of… … PLANE TRIGONOMETRY. 315 It is manifest, from Def. 4. that CD is the sine of the an2;le CBF.Let Cj3 be pioihiced till it meet the circle again in i; and it is alsomanifest, that AK is the tans^ent, and BE the secant, of the ancleAiil, or CBF, from Def. 6. 7. Cor. to Def. 4,5,6,7. The sine,…
Euclid's Elements · Geometry · Trigonometry
Internet Archive · Public Domain Mark 1.0. Free to use for anything.
![An illustration from Nicolai Copernici Torinensis De reuolutionibus orbium coelestium, libri VI : Habes in hoc opere iam recens nato, & aedito, studiose lector, motus stellarum, tam fixarum, quàm erraticarum, cum ex ueteribus, tum etiam ex recentibus obseruationibus restitutos: & nouis insuper ac admirabilibus hypothesibus ornatos. Habes etiam tabulas expeditissimas, ex quibus eosdem ad quoduis tempus quàm facillime caculare poteris. Igitur eme, lege, fruere. [Line in Greek] (1543)](https://img.insideoutlibrary.com/img/200/ia-nicolaicopernici00cope-63-39.webp)
![An illustration from L'optique divisée en trois livres : ou, l'On démontre d'une maniere aisée tout ce qui regarde 1. la propagation & les proprietez de la lumiere. 2. La vision. 3. La figure & la disposition des verres qui servent à la perfefectionner [sic] (1682)](https://img.insideoutlibrary.com/img/200/ia-loptiquedivise00ango-177-18.webp)
