Question

calcule tg (x+y) e tg (x-y):
a) tg x = 3 e tg y = 2
b)tg x = -5 e tg y = -4

Answer 1

a) tg(x+y) = (tgx+tgy)/(1-tgx.tgy) = (3+2)/(1-3.2) =  5/(1-6) = 5/-5 = -1
    tg(x-y) = (tx-tgy)/(1+tgx.tgy) = (3 - 2)/(1 + 3.2) = 1/7