A basic review of circles and how to calculate the circumference, radius, diameter, and area. Includes practice questions.

Rather than dividing a circle into some number of segments (like 360 degrees), mathematicians often prefer to measure angles using the circumference of a unit circle - a circle with radius 1. This way of measuring angles is called...

Need some ideas for Pi Day on March 14th? You can get some great resources at this location. There are all kinds of links available.

Learn about the radius of a circle with this useful reference guide. Provides a detailed definition, examples, and an interactive activity that enhances further explanation. Includes links to related topics.

For this task, students investigate and develop an understanding of the formula for the area of a circle. Aligns with G-GMD.A.1.

This tutorial provides a brief introduction about what area is, then gives the formulas for area of a square, rectangle, parallelogram, trapezoid, triangle, and circle. Examples of each formula are provided.