Решите пожалуйста... (10 класс)

1.
$ctg 3x= \sqrt{3} \\ 3x = \frac{\pi}{6} + 2\pi \cdot n \: n \in Z \\ x = \frac{\pi}{18} + \frac{2\pi}{3} \cdot n \: n \in Z$

2.
$sin (3-2x)=- \frac{ \sqrt{2} }{2} \\ 3-2x1 = - \frac{\pi}{4} + 2\pi n \\ 3-2x2 = \frac{5\pi}{4} + 2\pi n \\ - 2x1 = - \frac{\pi}{4} - 3 + 2\pi n \\ - 2x2 = \frac{5\pi}{4} - 3 + 2\pi n \\ \\ x1 = \frac{\pi}{8} + \frac{3}{2} - \pi n \\ x2 = - \frac{5\pi}{8}+ \frac{3}{2} - \pi n \\$

3.
$cos(\pi \sqrt{x}) =- \frac{ \sqrt{3} }{2} \\ \pi \sqrt{x} = \pm\frac{5\pi}{6} + 2\pi n \\ \sqrt{x} = \pm\frac{5}{6} + 2n \\ x = (\pm\frac{5}{6} + 2n)^{2} = \frac{25}{36} + 4n^{2} \pm{1\frac{2}{3}n}$