## Precalculus (6th Edition) Blitzer

The rectangular equation is, ${{x}^{2}}+{{y}^{2}}=y$
Using, ${{r}^{2}}={{x}^{2}}+{{y}^{2}}$ we will convert the polar equation to the rectangular equation. Therefore, \begin{align} & r=\sin \theta \\ & {{r}^{2}}=r\sin \theta \\ & {{x}^{2}}+{{y}^{2}}=r\sin \theta \\ & =y \end{align}