Answer
(a), (b), and (d)
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$$(7, 140^{\circ })= (7, 140^{\circ }+2(-1)180^{\circ })=(7, -220^{\circ }) \\ (7, 140^{\circ })= (-7, 140^{\circ } + 180^{\circ } +2(0)180^{\circ })=(-7, 320^{\circ }) \\ (7, 140^{\circ })= (-7, 140^{\circ }+180^{\circ }+2(-1)180^{\circ })=(-7, -40^{\circ})$$
