Question

Помогите решить две задачи

Answer 1

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

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