Question

Помогите решить ЕГЭ по математике

Answer 1

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