1074(2,4) ПОМОГИТЕ ПОЖАЛУЙСТА!!!

Решите задачу:

$1074.\;2)\;-\sin(\pi-\alpha)+tg(\alpha-\pi)-\cos\left(\frac\pi2+\alpha\right)=\\=-\sin(\pi-\alpha)-tg(\pi-\alpha)-\cos\left(\frac\pi2+\alpha\right)=-\sin\alpha+tg\alpha-\sin\alpha=\\=tg\alpha-2\sin\alpha=\frac{\sin\alpha}{\cos\alpha}-2\sin\alpha=\frac{\sin\alpha-2\sin\alpha\cos\alpha}{\cos\alpha}=\frac{\sin\alpha-\sin2\alpha}{\cos\alpha}$
$4)\;\cos\beta\cdot tg(\pi+\beta)\cdot tg\left(\frac{3\pi}2-\beta\right)\cdot cosec\left(\frac\pi2-\beta\right)=\\=\cos\beta\cdot tg(\pi+\beta)\cdot tg\left(\frac{3\pi}2-\beta\right)\cdot\frac1 {\sin\left(\frac\pi2-\beta\right)}=\\=\cos\beta\cdot tg\beta\cdot ctg\beta\cdot\frac1{\cos\beta}=1$