a) \[x = \frac{\pi}{6} + 2k\pi \lor x = \frac{5\pi}{6} + 2k\pi, k \in \mathbb{Z}\]
b) \[x = \frac{3\pi}{4} + 2k\pi \lor x = \frac{5\pi}{4} + 2k\pi, k \in \mathbb{Z}\]
c) \[x = \frac{\pi}{3} + k\pi, k \in \mathbb{Z}\]
d) \[x = \frac{\pi}{3} + 2k\pi \lor x = \frac{2\pi}{3} + 2k\pi \lor x = \frac{4\pi}{3} + 2k\pi \lor x = \frac{5\pi}{3} + 2k\pi, k \in \mathbb{Z}\]
e) \[x = \frac{\pi}{4} + \frac{k\pi}{2}, k \in \mathbb{Z}\]
f) \[x = \frac{\pi}{3} + k\pi \lor x = -\frac{\pi}{3} + k\pi, k \in \mathbb{Z}\]
