# How do you convert r=-4cos(theta) into cartesian form?

Jun 5, 2016

${x}^{2} + {y}^{2} + 4 x = 0$

#### Explanation:

To convert polar form of equation to Cartesian form, one can use $r \cos \theta = x$ and $r \sin \theta = y$. From this we also get ${r}^{2} = {x}^{2} + {y}^{2}$.

Hence, $r = - 4 \cos \theta$ can be written as

${r}^{2} = - 4 r \cos \theta$ or

${x}^{2} + {y}^{2} = - 4 x$ or

${x}^{2} + {y}^{2} + 4 x = 0$