Question

Помогите с тригонометрией, пожалуйста
б) (sin^2a+tg^2a*sin^2a)*ctg a
    в) ((sin^2t - 1)/(cos^4t))+tg^2t

Answer 1

sin^2a(1+tg^2a)*ctga=(1/cos^2a)*sinacosa=sina/cosa=tga
(sin^2t-1+tg^2tcos^4t)/cos^4t=(sin^2t-1+cos^2tsin^2t)/cos^4t=(sin^2tcos^2t-cos^2t)/cos^4t=
=(sin^2t-1)/cos^2t=-cos^2t/cos^2t=-1