This video explains how to use drawing tools on a computer to draw circles and their parts. As you watch and listen to the teacher and student interact it helps clarify the thinking behind applying this concept. [5:59]

Similarity and the Golden ratio join forces again, this time to save the Earth! (Or maybe just finding its radius.)

Given this lesson and either the diameter or radius of a circle, you'll be able to calculate the other measure.

Given this lesson and either the diameter or radius of a circle, you'll be able to calculate the other measure.

Given this lesson and either the diameter or radius of a circle, you'll be able to calculate the other measure. It is 4 of 10 in the series titled "Converting Between Diameter and Radius." [2:01]

Given this lesson and either the diameter or radius of a circle, you'll be able to calculate the other measure. It is 7 of 10 in the series titled "Converting Between Diameter and Radius." [1:56]

Given this lesson and either the diameter or radius of a circle, you'll be able to calculate the other measure. It is 8 of 10 in the series titled "Converting Between Diameter and Radius." [2:33]

In this tutorial you will learn how to find the volume of an object as well as how to use the volume equation to find the radius of a sphere using cubed roots. Student watch a video tutorial and then take an online quiz.

This video lesson describes the term central angle.

This video explains circumference, radius and diameter in an appealing way for students to understand.

This resource provides a short video about area formulas.