So I'm trying to figure out what the angle $θ$ would equal at $x=-2$ for the polar equation $r=θ+sin(2θ)$.
All I know is that $θ$ has a domain of $0\leθ\le \pi$ and $y < 1$ (pretty sure).
I think I either have to convert the equation into Cartesian form (but I can't figure out how to do that) or find the argument θ=arctan(y/x) with an unknown y, which I also can't figure out how to do...
I also know that $ x = r cos (\theta)$ and $x = -2$ into polar form is $x = 2 cis (\pi)$