# How do you convert x^2+y^2=9 into cartesian form?

Nov 6, 2016

The equation ${x}^{2} + {y}^{2} = 9$ is already in Cartesian form.

#### Explanation:

The equation ${x}^{2} + {y}^{2} = 9$ is already in Cartesian form.

The relation between Cartesian coordinates $\left(x , y\right)$ and polar coordinates $\left(r , \theta\right)$ is

$x = r \cos t \eta$ and $y = r \sin \theta$ i.e. ${x}^{2} + {y}^{2} = {r}^{2}$

Hence equation in Cartesian form ${x}^{2} + {y}^{2} = 9$ can be written in polar form as ${r}^{2} = 9$ or $r = 3$