Question

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

Answer 1

`6\pi` in

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\\√(9) = r\\3 = r`

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

=
`2*\pi *3`

=
`6\pi` in