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.

Video Examples: How to Find a Radius Between Two Points

Solved Example on Radius

Ques: Find the radius of a circle with area 153.86 square inches. Take p = 3.14

    A. 8
    B. 7
    C. 6
    D. 5
    Correct answer: B


    Step 1: Area of a circle of radius r = p 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.]