Here is a site that clearly and thoroughly explains the radian measure of angles. There are example problems solved, problems for the student to attempt, and answers to the student problems.

This site provides two geometry problems involving circles. One problem has the reader find the arc length given the angle and radius, the other problem has the reader find the measure of the angle given the arc length and radius....

Learn about sectors with this handy reference guide. Provides a detailed definition and an interactive activity that enhances further explanation. Includes links to related topics.

For this task, students use a piece of string or another tool to measure the radius of the circle and then mark off the corresponding arc length on the unit circle as many times as they need to for 0, 1, 2, 3, 4, 5, and 6 radians. They...