Algebra and Trigonometry 10th Edition

(a)$-\frac{\pi}{5}$ lies in the Fourth Quadrant. (b) $\frac{7\pi}{5}$ lies in the Third Quadrant.
If $θ$ lies in the: - First Quadrant, then $0\ltθ\lt\frac{\pi}{2}$ - Second Quadrant, then $\frac{\pi}{2}\ltθ\lt\pi$ - Third Quadrant, then $\pi\ltθ\lt\frac{3\pi}{2}$ - Fourth Quadrant, then $\frac{3\pi}{2}\ltθ\lt2\pi$ (a) $-\frac{\pi}{5}+2\pi=\frac{9\pi}{5}$ $\frac{3\pi}{2}\lt\frac{9\pi}{5}\lt2\pi$ , so $-\frac{\pi}{5}$ lies in the Fourth Quadrant. (b) $\pi\lt\frac{7\pi}{5}\lt\frac{3\pi}{2}$, so $\frac{7\pi}{5}$ lies in the Third Quadrant.