In the first, top rated, comment on the original post linked below, the author wrote the function $r = \dfrac {\cos(x)} {1−\cos(x)}$. I do not understand how they got to this equation. I get how they solved for $x$ in their first step. Can you please explain how they solved for $r$.
This is the picture of the problem, where we are solving for $r$, given $x = \dfrac {n-2}{2n}$
Original Post Numbers of circles around a circle