# How do you convert r=cos(theta) in rectangular form?

##### 1 Answer
Dec 4, 2015

${x}^{2} + {y}^{2} = x$

#### Explanation:

Multiply both sides by $r$:

${r}^{2} = r \cos \left(\theta\right)$

Use the formulas ${r}^{2} = {x}^{2} + {y}^{2}$ and $x = r \cos \left(\theta\right)$:

${x}^{2} + {y}^{2} = x$