Answer
$a.$
$(2,\displaystyle \frac{\pi}{3}), \quad (2,\frac{7\pi}{3})\quad (-2,\frac{4\pi}{3})$ all represent the same point A.
$b.$
$(1,-\displaystyle \frac{3\pi}{4}), \quad(1,\frac{5\pi}{4}), \quad(-1,\frac{\pi}{4}), \quad$all represent the same point $B.$
$c.$
$(-1,\displaystyle \frac{\pi}{2}), \quad (-1,\frac{5\pi}{2}),\quad (+1,\frac{3\pi}{2}),$ all represent the same point $C$.
Work Step by Step
$(r,\theta\pm 2k\pi),\ k\in \mathbb{Z}$ and $(r,\theta)$ represent the same point
$(-r,\theta\pm 2k\pi),\ k\in \mathbb{Z}$ represent the point symmetric to $(r,\theta)$, over the pole (origin).
$(r,\theta\pm(2k+1)\pi),\ k\in \mathbb{Z}$ represent the point symmetric to $(r,\theta)$, over the pole (origin).
$(-r,\theta\pm(2k+1)\pi),\ k\in \mathbb{Z}$ and $(r,\theta)$ represent the same point.
Leaving the same r, adding an even multiple of $\pi$ to $\theta$ yields the same point.
Changing the sign of r, adding an odd multiple of $\pi$ to $\theta$ yields the same point.
$a.$
$(2,\displaystyle \frac{\pi}{3}), \quad (2,\frac{7\pi}{3})\quad (-2,\frac{4\pi}{3})$ all represent the same point A.
$b.$
$(1,-\displaystyle \frac{3\pi}{4}), \quad(1,\frac{5\pi}{4}), \quad(-1,\frac{\pi}{4}), \quad$all represent the same point $B.$
$c.$
$(-1,\displaystyle \frac{\pi}{2}), \quad (-1,\frac{5\pi}{2}),\quad (+1,\frac{3\pi}{2}),$ all represent the same point $C$.
