Follow Us on Twitter

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

What Is the Diameter in Terms of the Circumference?

The diameter of a circle is the circumference of a circle divided by π.

How to Find the Diameter from the Circumference

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



Step 1: Divide the circumference, C, by π.
C ÷ π = Cπ

This is the diameter, d, of the circle.

A Real Example of How to Find the Diameter from the Circumference

Question: What is the diameter of the circle, with circumference 30cm, below?



Step 1: Divide the circumference, 30cm, by π.
30 ÷ π = 30 ÷ 3.14 = 9.6cm

The diameter of the circle is 9.6cm.
Curriculum
Geometry Lessons
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.



The diameter is the line through the center of the circle that has its endpoints on the circle.