# What is the equation of circle with center at (0,0) and radius of 7?

Jan 26, 2016

${x}^{2} + {y}^{2} = 49$

#### Explanation:

The standard form of a circle with a center at $\left(h , k\right)$ and a radius $r$ is

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

Since the center is $\left(0 , 0\right)$ and the radius is $7$, we know that

$\left\{\begin{matrix}h = 0 \\ k = 0 \\ r = 7\end{matrix}\right.$

Thus, the equation of the circle is

${\left(x - 0\right)}^{2} + {\left(y - 0\right)}^{2} = {7}^{2}$

This simplifies to be

${x}^{2} + {y}^{2} = 49$

graph{(x^2+y^2-49)=0 [-16.02, 16.03, -8.01, 8.01]}