Question

Мне только 3 обведенное вверху

Answer 1

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

$tg^4 \alpha =tg^4 \alpha$