Question

tgальфа(1+cos2алтфа)=sin2альфа

Answer 1

cos2a=cos^2a-sin^2a

sin2a=2sina*cosa

tga=sina/cosa

cos^2a-sin^2a+2sina*cosa*sina/cosa=cos^2a-sin^2a+2sin^2a=cos^2a+sin^2a=1