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 320
n ^ (CDB+CBD):tan h (CDB-CBD) : : R : tan (45°-CBD), (2 Cor. Prop. 3.);therefore, R : tan (45°-CBD) : : tan ^ (CAB+CBA):tan I (CAB —CBA); and CBD was already shown to be such an an*gk that BC : C A : : R : tan CBD. Therefore, &c. Q. E. D. Cor. If BC, CA, and the angle C are given to find the… … 330 NOTES. SPH. TRIGONOMETRY. In reading the elements of Plane Trigonometry, it may be of us*to observe, that the first five propositions contain all the rules abso-lutely necessary for solving the different cases of plane triangles. Thelearner, when he studies Trigonometry for the hrst time^ may…
Euclid's Elements · Geometry · Trigonometry
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