Question

Ctgx/ctgx+tgx= как решить?(

Answer 1

$frac{ctgx}{ctgx+tgx}=frac{ctgx}{ctgx+frac{1}{ctgx}}=frac{ctg^2x}{ctg^2x+1}=frac{ctg^2x}{frac{1}{sin^2x}}=ctg^2xcdot sin^2x=\\=frac{cos^2x}{sin^2x}cdot sin^2x=cos^2x$