Question

Срочно очень надо!!!​

Answer 1

$Ctg(\frac{\pi }{2}+\alpha)*tg(\frac{3\pi }{2}-\alpha)+Sin^{2}\alpha=-tg\alpha*Ctg\alpha+Sin^{2}\alpha=-1+Sin^{2}\alpha=-(1-Sin^{2}\alpha)=-Cos^{2}\alpha$