Question

Помогите решить, алгебра 10 класс​

Answer 1

$3)\frac{2Cos^{2}\alpha-1}{1-2Sin^{2}\alpha} -Sin^{2}\alpha=\frac{Cos2\alpha }{Cos2\alpha } -Sin^{2}\alpha=1-Sin^{2}\alpha =Cos^{2}\alpha\\\\4)\frac{tg^{4}x-tg^{6}x}{Ctg^{4}x-Ctg^{2}x}=\frac{tg^{4}x(1-tg^{2}x)}{\frac{1}{tg^{4} x}-\frac{1}{tg^{2}x }}=\frac{tg^{4}x(1-tg^{2}x)}{\frac{1-tg^{2}x }{tg^{4}x }}=\frac{tg^{4} x(1-tg^{2}x)*tg^{4}x}{1-tg^{2}x }=tg^{8}x$