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 220
The sura of any two sides of a triangle is to their dif-ference, as the tangent of half the sum of the angles op-posite to those sides, to the tangent of half their difference. Let ABC be any plane triangle;CA+AB : CA—AB :: tan.^ (B+C): tan. i (B—C).For (2.) CA: ABrisin. B: sin. C;and therefore (E.… … Otherwise, without the 3d. Let ABC be a triangle; the sum of AB and AC any two shies, isto the difference of AB and AC as the tangent of half the sum of theangles ACB and ABC, to the tangent of half their difference. 220 PLANE TRIGONOMETRY. About the centre A with the radius AB, the greater of the…
Euclid's Elements · Geometry · Trigonometry
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