Answer
(a) and (b)
Work Step by Step
Please note that if $n$ is any integer, the point $(r, \theta )$ can be represented as$$(r, \theta ) = (r, \theta +2n\pi ) \\ \text{or} \\ (r, \theta )= (-r, \theta +\pi + 2n\pi ).$$So we have$$(-5, -\frac{\pi }{4})= (-5, -\frac{\pi }{4}+2(1)\pi)=(-5, \frac{7\pi }{4}) \\ (-5,
-\frac{\pi }{4})= (-(-5), -\frac{\pi }{4}+\pi +2(-1)\pi )=(5, -\frac{5\pi }{4}).$$
