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 258
I BAC : tan. h (BAD + CAD).For in the triangle BAC (37.), tan. B : tan.C :: sin. CD : sin.BD,andtherefore(E.0.),tan. C+tan.B : tan.C—tan.B sin.BD+sin.CD : sin. BD —sin. CD. Now, (hy tlie annexed Lemma) tan.C-f tan.B : tan. C-tan. B :: sin. (C-f-B)*: sin. (C-B), and sin. BD+sin.CD : sin. BD-sin. CD…
Euclid's Elements · Geometry · Trigonometry
Internet Archive · Public Domain Mark 1.0. Free to use for anything.
