## Precalculus (6th Edition) Blitzer

The rectangular equation is, ${{x}^{2}}+{{y}^{2}}=100$
Using ${{r}^{2}}={{x}^{2}}+{{y}^{2}}$, we will convert the polar equation to the rectangular equation. Therefore, \begin{align} & {{x}^{2}}+{{y}^{2}}={{10}^{2}} \\ & {{x}^{2}}+{{y}^{2}}=100 \\ \end{align}