In the book Elementary Algebra for College Students , Allen R. Angel discusses the formula for area and circumference, which you can use to measure a hockey puck (144).

The line is labelled radius. Written below: C equals two pi r., The formula for the circumference of a circle uses either the diameter or the radius of the circle.

Learn about and revise circles and their properties such as circumference and radius with this BBC Bitesize GCSE Maths OCR study guide.