Question

If the diameter of a circle is 22, what is the circumference?

Answer 1

See a solution process below:

Explanation:

The relationship between the diameter and the radius is:

`d = 2r`

The formula for the circumference of a circle is:

`C = 2pir` or `C = 2rpi`

Because `d = 2r` we can substitute as:
`C = dpi`

We can now calculate the circumference of the circle in the problem as:

`C = 22pi`

If we want to approximate `pi` as 3.14 we get:

`C ~= 22 * 3.14`

`C ~= 69.08`