Davies, Charles, 1798-1876 · New York and Chicago, A. S. Barnes and company · leaf 191
ual to the less side BC, as a radius,describe the arc DI: and with B asa centre and the equal radius BC, ^ EI L F describe the arc CL: now DE is the sine of the angle A,and CF is the sine of B, to the same radius AD or BCBut by similar triangles, AD : DE : : AC : CF.But AD being equal to BC, we… … In any triangle, the sum of the two sides containing eitherangle, is to their difference, as the tangent of half the sum ofthe two other angles, to the tangent of half their difference.Let ACB be a triangle: then willAB + AC: AB-AC: : tan i(C + B) With A as a centre, and a radiusAC the less of the…
Geometry · Plane trigonometry
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