The Lesson
The diameter 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.Question
What is the diameter of the circle, with area 50 cm2, below?Step-by-Step:
1
Start with the formula:
Diameter = 2√ (A⁄π)
Don't forget: √ means square root, / means ÷ and π is pi (≈ 3.14)
2
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