Definition of Radius

  • Radius is the distance from the center of a circle or a sphere to any point on the circle or a sphere.
  • In other words, radius is a line segment joining the center of a circle with any point  on the circle.


Examples of Radius

  • is a radius of the circle shown.

Solved Example on Radius

Find the radius of a circle with area 153.86 square inches.


A. 8

B. 7

C. 6

D. 5

Correct answer: C


Step 1: Area of a circle of radius                          [Original equation.]

Step 2: 153.86 =                        [Substitute values.]

Step 3:                     [Divide each side by 3.14.]

Step 4:                                         [Simplify.]

Step 5:                                   [Evaluate square root on both sides.]

Step 6: r = 7                                      [Ignore the negative value.]


Related Terms for Radius

  • Line Segment
  • Center
  • Circle
  • Sphere


Additional Links for Radius