# How do you find the equation of the circle given r=4; C(3,-4)?

Jun 16, 2016

${\left(x - 3\right)}^{2} + {\left(y + 4\right)}^{2} = 16$

#### Explanation:

The standard form of the equation of a circle is.

$\textcolor{red}{| \overline{\underline{\textcolor{w h i t e}{\frac{a}{a}} \textcolor{b l a c k}{{\left(x - a\right)}^{2} + {\left(y - b\right)}^{2} = {r}^{2}} \textcolor{w h i t e}{\frac{a}{a}} |}}}$
where (a ,b) are the coordinates of the centre and r, the radius.

here a = 3 , b = -4 and r = 4

Substitute these values into the standard equation.

${\left(x - 3\right)}^{2} + {\left(y + 4\right)}^{2} = 16 \text{ is the equation}$