Question

Как упростить?

Answer 1

B$2tg(\frac{\pi}{4}- \alpha )\cdot cos^2(\frac{\pi}{4}- \alpha )=2\frac{sin(\frac{\pi}{4}- \alpha )}{cos(\frac{\pi}{4}- \alpha )}\cdot cos^2(\frac{\pi}{4}- \alpha )=\\\\=2sin(\frac{\pi}{4}- \alpha )\cdot cos(\frac{\pi}{4}- \alpha )=sin(\frac{\pi}{2}-2 \alpha )=cos2 \alpha$