1.2 Trigonometric Functions

1.
(a) $\displaystyle{\frac{\pi}{6}}$ (b) $\displaystyle{\frac{2\pi}{9}}$ (c) $\displaystyle{\frac{2\pi}{5}}$
2.
(a) $\displaystyle{\frac{\pi}{3}}$ (b) $\displaystyle{\frac{\pi}{6}}$
3.
(a) $\displaystyle{[0, \frac{\pi}{6})\cup (\frac{11\pi}{6},2\pi]}$ (b) $\displaystyle{(\frac{\pi}{6}, \frac{\pi}{2}) \cup (\frac{7\pi}{6}, \frac{3\pi}{2})}$ (c) $\displaystyle{(\frac{\pi}{6}, \frac{\pi}{3}) \cup (\frac{2\pi}{3}, \frac{5\pi}{6})}$
4.
(a) $\displaystyle{0}$ (b) $\displaystyle{\frac{\pi}{6}}$ (c) $\displaystyle{\frac{\sqrt{3}}{2}}$