Measure of a Circle

Measure of a Circle

Number, called the circumference, that expresses the length of a circle.


The formula to calculate the circumference of a circle is: C = 2πr = πd.


  • 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.

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