Question

Задание прикреплено ниже.

Answer 1

на фото................

Answer 2

$4)\frac{1-Cos2\alpha+Sin2\alpha}{1+Cos2\alpha+Sin2\alpha}*Ctg\alpha =\frac{2Sin^{2}\alpha+2Sin\alpha Cos\alpha}{2Cos^{2}\alpha+2Sin\alpha Cos\alpha}*Ctg\alpha=\frac{2Sin\alpha(Sin\alpha+Cos\alpha)}{2Cos\alpha(Cos\alpha+Sin\alpha)}*Ctg\alpha=\frac{Sin\alpha }{Cos\alpha }*Ctg\alpha=tg\alpha*Ctg\alpha=1\\\\1=1$

Тождество доказано

$6)1-2Sin^{2}(\frac{\pi }{4}-\frac{\alpha }{2})=Cos(2*(\frac{\pi }{4}-\frac{\alpha }{2}))=Cos(\frac{\pi }{2}-\alpha)=Sin\alpha\\\\Sin\alpha=Sin\alpha$

Тождество доказано