you just sorta gotta common sense a lot of it

for quadrant 2, x is always negative whilst the argument is always positive so that’s obviously not included

for quadrant 4, x is always positive whilst the argument is always negative so that’s always included.

for quadrant 1, when x is greater than pi/2 it’s included since the argument won’t exceed pi/2 there, but the region from 0 to pi/2 is a little more complicated. tan(theta)=y/x, but theta>=x, so tan(theta)>=tan(x) and therefore tan(x)<=y/x. hence xtan(x)>=y and from there the rest is trivial, just graph xtan(x)=y within that region

for quadrant 3, the argument is always less than -pi/2 so any x values greater than or equal to that are ofc included. then beyond that it’s the same deal as previously, make an equation with y and x using the fact that theta>=x and you’re good