.

1.2 Trigonometric Functions

1.

(a) $${\frac{\pi}{6}}$$ (b) $${\frac{2\pi}{9}}$$ (c) $${\frac{2\pi}{5}}$$

2.

(a) $${\frac{\pi}{3}}$$ (b) $${\frac{\pi}{6}}$$

3.

(a) $${[0, \frac{\pi}{6})\cup (\frac{11\pi}{6},2\pi]}$$ (b) $${(\frac{\pi}{6}, \frac{\pi}{2}) \cup (\frac{7\pi}{6}, \frac{3\pi}{2})}$$ (c) $${(\frac{\pi}{6}, \frac{\pi}{3}) \cup (\frac{2\pi}{3}, \frac{5\pi}{6})}$$

4.

(a) $${0}$$ (b) $${\frac{\pi}{6}}$$ (c) $${\frac{\sqrt{3}}{2}}$$