Plot the point whose spherical coordinates are given. Then find the rectangular coordinates of the point.
(a) \(\left(7, \frac{3\pi}{4}, \frac{\pi}{2}\right)\)
(x, y, z) = \left(\frac{-7\sqrt{2}}{2}, \frac{7\sqrt{2}}{2}, 0\right)
(b) \left(8, -\frac{\pi}{3}, \frac{\pi}{4}\right)
(x, y, z) = \left(\boxed{\qquad}\right)