Question

tg x + tg2x /1-tgx tg2x = 1

Answer 1

$frac{tgx+tg2x}{1-tgxtg2x} =1\ \ tg(x+2x)=1\ \ tg3x=1\ \ 3x= frac{pi}{4}+ pi n,n in mathbb{Z}~~~|:3\ \ x= frac{pi}{12} + frac{pi n}{3},n in mathbb{Z}$