Concentric circles


Concentric circles are coplanar circles that share the same center. However, radii of concentric circles are not congruent or equal.

Concentric circlesConcentric circle


The circles above are examples of concentric circles. Notice that the radius of the smaller circle is shown in black while the radius of the big circle is shown in red. 

The region outside the smaller circle but inside the big circle is called annulus. 

To name a circle, we use the name of the center. Since concentric circles have the same center, you may wonder how to name concentric circles.

You may use the radii to that end!

For example, to name the big circle, you could say circle with center A and radius Y.

Recent Articles

  1. How To Find The Factors Of 20: A Simple Way

    Sep 17, 23 09:46 AM

    Positive factors of 20
    There are many ways to find the factors of 20. A simple way is to...

    Read More

  2. The SAT Math Test: How To Be Prepared To Face It And Survive

    Jun 09, 23 12:04 PM

    SAT math
    The SAT Math section is known for being difficult. But it doesn’t have to be. Learn how to be prepared and complete the section with confidence here.

    Read More

Tough algebra word problems

100 Tough Algebra Word Problems.

If you can solve these problems with no help, you must be a genius!

Math quizzes

 Recommended

Math vocabulary quizzes