Question

A circular light fixture has a radius of 20 centimeters.what is the circumference of the light fixture

Answer 1

`\boxed {\boxed {\sf 40 \pi \ cm, 125.6 \ cm, or \ 125.6637061 \ cm}}`

Explanation:

Circumference can be found by multiplying the diameter of the circle by pi.

`c= \pi d`

We are given the radius, which is 20 centimeters. We need the diameter, which is twice the radius.

`d= 2r`

`d= 2(20 \ cm)`

`d= 40 \ cm`

Substitute the diameter into the formula. There are many ways to calculate circumference, so I included a few options.

1. In Terms of Pi

If we solve in terms of pi, we leave π in the answer.

`c=\pi ( 40 \ cm)`

`c= 40 \pi \ cm`

2. Using 3.14 as Pi

`c=\pi ( 40 \ cm)`

Substitute 3.14 in for pi.

`c= (3.14)(40 \ cm)`

`c=125.6 \ cm`

3. Using 3.14159 as PI

`c=\pi ( 40 \ cm)`

Use the pi button on a calculator.

`c= 125.6637061 \ cm`

The circumference of the light fixture is 40π, 125.6 cm, or 125.6637061 cm