Not an answer - just want to note that the curve has more hidden branches. They can be seen looking at the parametric equation $$ x=\frac{\sin(\varphi)}\varphi,\quad y=\frac{1-\cos(\varphi)}\varphi $$ where $\varphi=2\theta$
Not an answer - just want to note that the curve has more hidden branches. They can be seen looking at the parametric equation $$ x=\frac{\sin(\varphi)}\varphi,\quad y=\frac{1-\cos(\varphi)}\varphi $$ where $\varphi=2\theta$