Question

помогите, срочно!!!!
-2√3cos (-19п/6)

Answer 1

$-2\sqrt3cos(-\frac{19\pi}{6})\\-2\sqrt3cos(-(9*2\pi+\frac{\pi}{6}))\\-2\sqrt3cos\frac{\pi}{6}\\-2\sqrt3*\frac{\sqrt3}{2}=-3$