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

Question

The circumference of a circle is 14.

How long is the circle's radius?

00:05 First, let's find the radius of the circle.

00:08 We'll use the formula for the circumference of a circle, which is two times pi times R.

00:17 Now, we'll take the given circumference, plug it into the formula, and solve for the radius.

00:23 Let's focus on isolating R, the radius.

00:28 And there we go! That's how you find the radius of a circle. Great job!

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:

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

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

$\frac{7}{\pi}$