Задание 4216

а) $\frac{\pi}{3} + 2\pi n,\ \frac{2\pi}{3} + 2\pi n,\ -\frac{\pi}{6} + 2\pi n,\ -\frac{5\pi}{6} + 2\pi n,\ n \in \mathbb{Z}$;

б) $\frac{19\pi}{6},\ \frac{23\pi}{6},\ \frac{13\pi}{3}$.