Age 16 to 18
The graph of $xy=0$ is the pair of lines $x=0$ and $y=0$. Similarly
you will need to draw a pair of graphs here but this time in polar
When you plot the point $(r,\theta)$ in polar coordinates, the
length of the line segment joining this point to the origin is $r$
and the angle between this line segment and the positive direction
of the $x$ axis is given by $\theta$.