Упрости выражения

1. \(\ctg \left(\pi -\alpha \right)-\sin \left(\dfrac{3\pi}{2}+\alpha \right)+\tg \left(\dfrac{5\pi}{2}-\alpha \right)+\cos \left(2\pi -\alpha \right)\) ;

2. \(\dfrac{\cos \left(\pi -\alpha \right)\sin \left(\dfrac{7\pi}{2}+\alpha \right)\cos \left(\dfrac{3\pi}{2}-\alpha \right)}{\ctg \left(5\pi -\alpha \right)\cos \left(4\pi -\alpha \right)\tg \left(3\pi +\alpha \right)}\) .

Ответ: 1) [ ]; 2) [ ].