Задание 4916

а) $\frac{\pi}{2}+2\pi n,\ -\frac{\pi}{6}+2\pi n,\ -\frac{5\pi}{6}+2\pi n,\ n\in\mathbb{Z}$

б) $-\frac{7\pi}{2};\ -\frac{17\pi}{6};\ -\frac{13\pi}{6}$