# How do you find the center and radius of the circle  x^2+y^2=4 ?

Jun 13, 2016

center $\left(0 , 0\right)$
Radius $= 2$

#### Explanation:

The general equation of a circle is:

${\left(x - a\right)}^{2} + {\left(y - b\right)}^{2} = {r}^{2}$

Where $\left(a , b\right)$ represent the coordinates of the center and $r$ is the radius.
Here in the equation:

${x}^{2} + {y}^{2} = 4$
${\left(x - 0\right)}^{2} + {\left(y - 0\right)}^{2} = {2}^{2}$

Therefore, the circle has :

center $\left(0 , 0\right)$
Radius $r = 2$