The Lesson
The radius of a circle is half of the diameter.
How to Find the Radius from the Diameter
Finding the radius from the diameter is easy.Question
What is the radius of the circle, with diameter 10 cm, below?
Step-by-Step:
1
Divide the diameter, 10 cm, by 2.
10 ÷ 2 = 5 cm
Answer:
The radius of the circle is 5 cm.Interactive Widget
Here is an interactive widget to help you learn about finding the radius of a circle from its diameter.Why Is Knowing the Radius in Terms of the Diameter Useful?
Most of the properties of a circle - such as its circumference and area - can be expressed in terms of the radius or diameter. Most students remember the area of a circle with a radius r as:
