# How do you write the equation of the circle with center (2, -1) and r = 8?

Jun 2, 2016

${\left(x - 2\right)}^{2} + {\left(y + 1\right)}^{2} = 64$

#### Explanation:

$C = \left(a , b\right) \text{ the center coordinates of circle}$

$a = 2 \text{ ," b=-1" ,} r = 8$

$r = \text{radius of circle}$

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

${\left(x - 2\right)}^{2} + {\left(y + 1\right)}^{2} = {8}^{2}$

${\left(x - 2\right)}^{2} + {\left(y + 1\right)}^{2} = 64$