Question

упростите выражение

Answer 1

$sin(5\pi -\alpha )*cos(\frac{3\pi} {2} +\alpha)-ctg(\frac{\pi} {2}- \alpha)+tg( \alpha -\pi)=$$=sin(\pi -\alpha )*cos(\frac{3\pi} {2} +\alpha)-ctg(\frac{\pi} {2}- \alpha)-tg(\pi-\alpha)= sin\alpha*sin\alpha-tg\alpha+tg\alpha=$$=sin\alpha*sin\alpha=sin^2\alpha$