Suppose the angle $\theta$ is in the fourth quadrant, $\frac{3\pi}{2} \leq \theta \leq 2\pi$, and $\displaystyle \tan(\theta) = \frac{-3}{7}.$ Find exact values (as fractions, not decimal approximations) for the following.

(a) $\sec(\theta)$ = help (fractions)

(b) $\sin(\theta)$ = help (fractions)