Докажите дождества: tg^2(a)-sin^2(a)=tg^2(a)*sin^2(a)

Question

Докажите дождества:

tg^2(a)-sin^2(a)=tg^2(a)*sin^2(a)

Answer 1

sin^2a(1/cos^2a-1)=sin^2a(1-cos^2a)/cos^2a=tg^2a*sin^2a