# How do you find the center and the length of the radius of x^2 + y^2 = 121?

May 13, 2018

$\text{centre } \left(0 , 0\right)$

$r = 11$

#### Explanation:

the standard equation of a circle centre $\left(a , b\right)$ and radius $r$

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

for

${x}^{2} + {y}^{2} = 121$

the centre is $\left(0 , 0\right)$

radius$r = \sqrt{121} = 11$