Answer
$(r,\pi+\theta)$ and $(-r,\theta)$.
Work Step by Step
The polar graphs in this section exhibit symmetry. Visualize an xy-plane superimposed on the polar coordinate system, with the pole at the origin and the polar axis on the positive x-axis. Then a polar graph may be symmetric with respect to the x-axis (the polar axis), the y-axis( the line $\theta=\frac{\pi}{2}$) , or the origin (the pole).
Since, the missing ordered pairs lies in third quadrant and where the polar coordinates are reflection to $(r,\theta)$ and lies in negative polar x-axis and therefore, the angles will be $(\pi+\theta)$ and $\theta$.
Hence the desired result will be $(r,\pi+\theta)$ and $(-r,\theta)$.
