# How do you write an equation of a circle with center (6,-9) and diameter = 2sqrt7?

Jan 29, 2016

${\left(x - 6\right)}^{2} + {\left(y + 9\right)}^{2} = 7$

#### Explanation:

The standard form of the equation of a circle is :

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

where ( a , b ) is the centre and r , the radius.

The data required to complete the equation is given in this

question , centre (6 , - 9 ) and r =$\sqrt{7}$

hence equation is : ${\left(x - 6\right)}^{2} + {\left(y + 9\right)}^{2} = {\left(\sqrt{7}\right)}^{2}$