# How to Find the Radius from the Circumference (Mathematics Lesson)

# What Is the Radius in Terms of the Circumference?

The radius of a circle is the circumference of a circle divided by 2π.# How to Find the Radius from the Circumference

**Question:**What is the radius of the circle, with circumference C, below?

**Step 1:**Divide the circumference, C, by 2.

C ÷ 2 =

^{C}⁄

_{2}

**Step 2:**Divide by π.

^{C}⁄

_{2}÷ π =

^{C}⁄

_{2π}

This is the radius, r, of the circle.

# A Real Example of How to Find the Radius from the Diameter

**Question:**What is the radius of the circle, with circumference 50cm, below?

**Step 1:**Divide the circumference, 50cm, by 2.

50 ÷ 2 = 25cm

**Step 2:**Divide by π.

25 ÷ π = 8cm

The radius of the circle is 8cm.

# Another Real Example of How to Find the Radius from the Circumference

The slider below shows another real example of how to find the radius of a circle from the circumference:##### Curriculum

##### Interactive Test

**show**

##### Note

**WHAT IS A CIRCLE?**

A circle is a shape containing a set of points that are all the same distance from the center. This distance is the radius.