(sin^2a+tg^2a•sin^2a)•ctga​

Question

(sin^2a+tg^2a•sin^2a)•ctga​

Answer 1

Sin^2 a(1+tg^2a)ctga=sin^2 a/cos^2 a) * ctga = tg^2a ctga=tga(tga ctga)=tga

Answer 2

(sin^2a+(sin^4a/cos^2a)*ctga= ((cos^2a*sin^2a+sin^4a)/cos^2a)*ctga=
(sin^2a(cos^2a+sin^2a)/cos^2a)*ctga=(sin^2a/cos^2a)*ctga=tg^2a*ctga=tga