Anonymous

tan A + tan B ------------------- 1 - tan A tan B 3/4 - 5/12 ------------------ 1 - (3/4)(-5/12) 1/3 ------------- 1 + 15/48 1/3 --------- 1 + 5/16 1/3 -------- 21/16 16 ---- 63

Anonymous

3,4,5 and 5,12,13 right triangles use that to get cosa and sinb, with quadrant info for correct signs Then use tanx = sinx/cosx to get tana and tanb, then use tan(a+b) = (tana+tanb) / (1-tana tanb).

Anonymous

Dipping into and out of complex numbers, we start with arg(4+3i) = a and arg(-12+5i) = b so a+b = arg((4+3i)(-12+5i)) = arg(-63-16i) and hence tan(a+b) = -16/-63 = 16/63

Anonymous

tan a = 3/4, tan b = -5/12 tan(a+b) = [3/4-5/12]/[1+15/48] = [1/3]/[63/48] = 16/63

Anonymous

tan(a)=3/4 tan(b)=-5/12 rule tan(a+b)=[tan(a)+tan(b)]/[1-tan(a)tan(b...