Circumference Study Guide

Circumference is the distance around the edge of a circle. It is similar to the perimeter of a polygon, but specifically refers to the boundary of a circle.

Formula for Circumference

The formula to find the circumference of a circle is:

C = 2πr

Where:

• C is the circumference
• π (pi) is a constant approximately equal to 3.14159
• r is the radius of the circle

Calculating Circumference

To calculate the circumference of a circle, you can use the formula C = 2πr, where r is the radius of the circle. If you are given the diameter (d) instead of the radius, you can use the formula C = πd.

Units of Circumference

The units of circumference are the same as the units of the radius. For example, if the radius is measured in meters, then the circumference will be in meters.

Practice Problems

1. Calculate the circumference of a circle with radius 5 cm.
Answer: C = 2π(5) = 10π cm

2. Find the circumference of a circle with diameter 12 inches.
Answer: C = π(12) = 12π inches

Summary

Understanding the concept of circumference is crucial when dealing with circles. The formula C = 2πr or C = πd is used to find the circumference, and it's important to pay attention to the units of measurement.