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. Take π = 3.14
A. 8
B. 7
C. 6
D. 5
Correct answer: B
Step 1: Area of a circle of radius r = π r2                          [Original equation.]
Step 2: 153.86 = 3.14 r2                       [Substitute values.]
Step 3:                     [Divide each side by 3.14.]
Step 4: 49 = r2                                        [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