of a circle
is found from the area
of a circle using the formula:
In this formula, A
is the area of the circle. The image below shows what we mean by finding the diameter from the circumference:
How to Find the Diameter from the Area
Finding the diameter from the area is easy.
What is the diameter of the circle, with area 50 cm2, below?
Start with the formula:
Diameter = 2√ (A⁄π)
√ means square root
, / means ÷ and
π is pi
Substitute the area into the formula. In our example, A = 50.
Diameter = √ (50⁄π)
Diameter = √ (50 ÷ π)
Diameter = √ (50 ÷ 3.14)
Diameter = √ 16 cm
Diameter = 4 cm
The diameter of the circle is 4 cm.
The slider below shows another real example of how to find the diameter of a circle from the area.
Here is an interactive widget
to help you learn about finding the diameter of a circle from its area.
Equivalent Formula for Finding the Diameter of a Circle from the Area
An equivalent formula for how to find the diameter of a circle from the area is:
This is equivalent as the square root of 4 is 2.