The LessonThe 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 AreaFinding the diameter from the area is easy.
QuestionWhat is the diameter of the circle, with area 50 cm2, below?
Start with the formula:
Diameter = 2√ (A⁄π)Don't forget: √ means square root, / means ÷ and π is pi (≈ 3.14)
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