The LessonThe diameter of a circle is found from the circumference of a circle using the formula:
In this formula, C is the circumference of the circle. The image below shows what we mean by finding the diameter from the circumference:
How to Find the Diameter from the CircumferenceFinding the diameter from the circumference is easy.
QuestionWhat is the diameter of the circle, with circumference 30 cm, below?
Start with the formula:
Diameter = C⁄πDon't forget: / means ÷ and π is pi (≈ 3.14)
Substitute the circumference into the formula. In our example, C = 30.
Diameter = 30⁄π Diameter = 30 ÷ π Diameter = 30 ÷ 3.14 Diameter = 9.6 cm