Radius of a Cylinder

The radius of a cylinder is the radius of the 2 bases found at the top and the bottom of the cylinder. It is the distance from the center of the cylinder to its edge. The radius is measured in units of length such as m, cm, mm, and ft. Shown below is the radius (r) of the given cylinder.

Let us now learn how to find the radius of a cylinder with formulas and solved examples.

Formula

The formula to calculate the radius of a cylinder is derived from the formula used to find the volume of a cylinder.

As we know,

Volume (V) = πr²h  

The above formula can be written in terms of radius (r), as follows

=> r² = V/πh

=> r = √V/πh

Thus, the equation to calculate the radius (r) of a cylinder = √V/πh, here V = volume, π = 22/7 = 3.141, h = height

Let us solve some examples to understand the concept better.

Solved Examples

Find the radius of a cylinder whose volume is 200 cubic units and the height is 5 units.

Solution:

As we know,
Radius (r) = √(V/π × h), here V = 200 cubic units, π = 3.141, h = 5 units
= √200/3.141 × 5
= √200/15.705
= √12.734
= 3.568 units

Calculate the radius of a cylinder having a volume of 100.15 cm³ and a height of 2.5 cm.

Solution:

As we know,
Radius (r) = √(V/π × h), here V = 100.15 cm³, π = 3.141, h = 2.5 cm
= √100.15/(3.141 × 2.5)
= √100.15/7.8525
= √12.753
= 3.571 cm