ПОМОГИТЕ!!!! СРОЧНО!!!!

Решите задачу:

$1)\; \; cos30^\circ +\frac{1}{2}\cdot tg(-\frac{\pi }{3})-cos\pi =\frac{\sqrt3}{2}-\frac{1}{2}\cdot tg\frac{\pi }{3}-(-1)=\\\\=\frac{\sqrt3}{2}-\frac{1}{2}\cdot \sqrt3+1=1\\\\2)\; \; \sqrt3\cdot cos\frac{7\pi }{6}+cos(-480^\circ )=\sqrt3\cdot cos(\pi +\frac{\pi}{6})+cos(360^\circ +120^\circ )=\\\\=\sqrt3\cdot (-cos\frac{\pi}{6} )+cos120^\circ =-\sqrt3\cdot \frac{\sqrt3}{2}+cos(180^\circ -60^\circ )=\\\\=-\frac{3}{2}-cos60^\circ =-\frac{3}{2}-\frac{1}{2}=-\frac{4}{2}=-2$