Question

№600. Вычислите:
а) cos 15п; B) cos(-33п/4);
б)sin 25п/2; г) sin(-19п/6).

Answer 1

$1) cos(15\pi)=cos(\pi)=-1$

$2) cos(-\frac{33\pi}{4})=cos(-8\frac{1}{4}\pi)=cos(\frac{7\pi}{4} )=cos(\frac{\pi}{4})=\frac{\sqrt{2}}{2}$

$3) sin(\frac{25\pi}{2})=sin(12\frac{1}{2}\pi)=sin(\frac{\pi}{2})=1$

$4)sin(-\frac{19\pi}{6})=sin(-3\frac{1}{6}\pi)=-sin(3\frac{1}{6}\pi)=-sin(\frac{7\pi}{6})=sin(\frac{\pi}{6}) =\frac{1}{2}$