Question

мне только 3 обведенное вверху

Answer 1

$frac{sin^2 alpha -cos^2 alpha +cos^4 alpha }{cos^2 alpha -sin^2 alpha +sin^4 alpha } = frac{sin^2 alpha -cos^2 alpha (1-cos^2 alpha )}{cos^2 alpha -sin^2 alpha (1-sin^2 alpha )} = frac{sin^2 alpha -cos^2 alpha cdot sin^2 alpha }{cos^2 alpha -sin^2 alpha cdot cos^2 alpha } =\\= frac{sin^2 alpha (1-cos^2 alpha )}{cos^2 alpha (1-sin^2 alpha )} = frac{sin^2 alpha cdot sin^2 alpha }{cos^2 alpha cdot cos^2 alpha } =frac{sin^4 alpha }{cos^4 alpha }=tg^4 alpha$

$tg^4 alpha =tg^4 alpha$