Number, called the circumference, that expresses the length of a circle.
Formula
The formula to calculate the circumference of a circle is: C = 2πr = πd.
- The letter C represents the circumference of the circle.
- The letter r represents the radius of the circle.
- The letter d represents the diameter of the circle.
- The value of π is approximately 3.1416.
Examples
- This circle has a radius of 3 centimetres.
C = 2πr
C ≈ 2 × 3.1416 × 3
C ≈ 18.8496 cm
- The circumference of the Earth is approximately 40 000 km.
