Answer
(a) $\sin{\frac{\pi}{2}}=0$
(b) $\cos{\frac{\pi}{2}}=-1$
(c) $\tan{\frac{\pi}{2}}=0$
Work Step by Step
Using Figure 13 on page 579 of this book, the angle $\pi$ 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, using the definitions above to obtain:
(a) $\sin{\frac{\pi}{2}}=0$
(b) $\cos{\frac{\pi}{2}}=-1$
(c) $\tan{\frac{\pi}{2}}=\dfrac{0}{-1}=0$
