Chapter 6 - 6.1 - Angles and Their Measure - 6.1 Exercises - Page 431: 51

(a) $\frac{13\pi}{6}$ $-\frac{11\pi}{6}$ (b) $\frac{7\pi}{6}$ $-\frac{17\pi}{6}$

(a) $\frac{\pi}{6}+2\pi=\frac{\pi}{6}+\frac{12\pi}{6}=\frac{13\pi}{6}$ $\frac{\pi}{6}-2\pi=\frac{\pi}{6}-\frac{12\pi}{6}=-\frac{11\pi}{6}$ (b) $-\frac{5\pi}{6}+2\pi=-\frac{5\pi}{6}+\frac{12\pi}{6}=\frac{7\pi}{6}$ $-\frac{5\pi}{6}-2\pi=-\frac{5\pi}{6}-\frac{12\pi}{6}=-\frac{17\pi}{6}$