## Precalculus (6th Edition)

(a) $\sin{3\pi}=0$ (b) $\cos{3\pi}=-1$ (c) $\tan{3\pi}=\dfrac{0}{-1}=0$
Using Figure 13 on page 579 of this book, the angle $3\pi$ intersects the unit circle at the point $(-1, 0)$. RECALL: In a unit circle, (1) $\cos{s} = x$ (2) $\sin{s} = y$ (3) $\tan{s} = \dfrac{y}{x}$ Thus, use the definitions above to obtain: (a) $\sin{3\pi}=0$ (b) $\cos{3\pi}=-1$ (c) $\tan{3\pi}=\dfrac{0}{-1}=0$