Задание 3417

а) $x = 2\pi k,\ x = \frac{\pi}{4} + 2\pi k,\ x = \frac{3\pi}{4} + 2\pi k,\ x = \pi + 2\pi k,\ k \in \mathbb{Z}$;

б) $x = \frac{11\pi}{4},\ x = 3\pi,\ x = 4\pi$.