# Given the area of a circle is 64(pi) how do you find the radius of the circle?

Jan 21, 2017

See the entire solution process below:

#### Explanation:

The formula for determining the area of a circle is:

$A = \pi {r}^{2}$

Substituting the value from the problem, $64 \pi$ for $A$ and solving for $r$ gives:

$64 \pi = \pi {r}^{2}$

We can divide each side of the equation by $\textcolor{red}{\pi}$

$\frac{64 \pi}{\textcolor{red}{\pi}} = \frac{\pi {r}^{2}}{\textcolor{red}{\pi}}$

$\frac{64 \textcolor{red}{\cancel{\textcolor{b l a c k}{\pi}}}}{\cancel{\textcolor{red}{\pi}}} = \frac{\textcolor{red}{\cancel{\textcolor{b l a c k}{\pi}}} {r}^{2}}{\cancel{\textcolor{red}{\pi}}}$

$64 = {r}^{2}$

We can now take the square root of each side of the equation to find the radius $r$:

$\sqrt{64} = \sqrt{{r}^{2}}$

$8 = r$

$r = 8$

The radius of the circle is $8$.