Calculate Circle Radius: Using Circumference = 14 and C = 2πr

Question

The circumference of a circle is 14.

How long is the circle's radius?

00:00 Find the circle's radius

00:03 We'll use the formula for calculating circle circumference

00:12 We'll substitute the given circumference value and solve for the radius

00:17 Let's isolate R

00:35 And this is the solution to the problem

We begin by using the formula:

$P=2\pi r$

We then insert the given data into the formula:

$14=2\times\pi\times r$

Lastly we divide Pi by 2:

$\frac{14}{2\pi}=\frac{2\pi r}{2\pi}$

$\frac{7}{\pi}=r$

$\frac{7}{\pi}$