Question

The area of a circle is 9π in². What is the circumference, in inches? Express your answer in terms of \piπ

Answer 1

Answer:

$6\pi$ in

Step-by-step explanation:

The formula to find the area of a circle: $\pi r^{2}$, where $r$ is the radius.

The formula to find the circumference (perimeter) of a circle: $2\pi r$, where $r$ is the radius.

1) To find the circumference of the circle, we need to find the radius ($r$) first. Since the area of the circle is given to us, we need to equate this to the formula to find the area of a circle.

$9\pi =\pi r^2$

Cancel the $\pi$ by bringing it to the other side.

$9 =\pi r^2$ ÷ $\pi$

$9 = r^2\\\sqrt{9} = r\\3 = r$

2) Find the circumference of the circle by using the formula, $2\pi r$.

=  $2*\pi *3$

= $6\pi$ in