How to Find the circumference of a circle in Geometry

In this tutorial the author shows how to find the circumference of a circle. He says that the circumference of a circle can be calculated by using the formula circumference C = 2 * Pi * R, where R is the radius of the circle. He shows how to solve these kind of problems using some examples and calculating the circumference by substituting the value of radius in the formula. This video gives a good introduction on how to find the circumference of a circle.