Question

What is the radius of a circle with a circumference of 28 pi?

Answer 1

The radius is `14` units.

Explanation:

Start by finding the diameter; the formula for circumference is `pid`, so set up an equality:

`28pi`=`c`
`28pi`=`pid`

Divide both sides by `pi`:

`(28pi)/(pi)=(pid)/(pi)`

`(28color(red)(cancel(pi)))/(color(red)(cancel(pi)))`=`(color(red)(cancel(pi))d)/(color(red)(cancel(pi)))`

`28=d`

Diameter is twice as large as radius, so divide your diameter by 2 to get radius.

`d/2=r=28/2=color(red)(14)`

Therefore, your radius is `14` units.