Question

Срочно!
(1+tg^2 α)cos^4 α+ sin^2 α=1.

Answer 1

1+tg^2(a) = sec^2(a) = 1/cos^2(a)
1/cos^2(a) * cos^4(a) = cos^2(a)
cos^2(a) + sin^2(a) = 1

Answer 2

Спасибо!!!