Question

What is the radius of a circle whose circumference is `16π`?

Answer 1

`8`

Explanation:

The circumference of a circle is equal to `pi`, which is a number `~~3.14`, multiplied by the diameter of the circle.

Therefore, `C=pid`.

We know that the circumference, `C`, is `16pi`, so we can say that:

`16pi=pid`

We can divide both sides by `pi` to see that `16=d`.

We now know that the diameter of the circle is `16`.

We also know that the diameter has twice the length of the radius.

In equation form: `2r=d`

`2r=16`

`color(red)(r=8`

Note that since `2r=d`, the equation `C=2pir` holds and can be used in place of `C=pid`.