This mini-lesson explores the area of a circle. Provides a definition, examples, and practice questions with answers.

Seventh graders will compare the formula for the area of a regular polygon to discover the formula for the area of a circle.

Demonstrates how to calculate the area of two-dimensional shapes using formulas. Covers parallelogram, triangle, trapezoid, and circle. Includes a video modeling how to find the area of a circle and a triangle. [0:59]

Explains formulas for areas of sectors of circles and lengths of arcs. Demonstrates how to use the formulas in each of degrees and radians.

This study guide on circumference and arc length covers key vocabulary, the parts of a circle, and formulas for circumference, area, and arc length. It is available for download with free registration.

This site from the Rice University includes a fill-in-the-blank lesson on the definition of circles, as Pythagoras described.

Use this circle calculator to find the area, circumference, radius, or diameter of a circle. Given any one variable A, C, r or d of a circle you can calculate the other three unknowns.

A complete reference guide to diameters. It provides definitions, examples, and interactive activities that enhance further explanation. Includes links to related topics.

In this instructional activity students will be engaged in an interactive online practice session using area and perimeter. Students will have to use critical thinking skills in order to unlock gates and learn more about the cups in the...

This exhibit is designed to show students that geometry really does apply to the real world. By taking viewers through a home decoration project, students learn how to calculate area of a rectangle and circle.

This CoolMath resource provides an introduction to some Precalculus formulas.

This site from the Math Forum defines both a circular cylinder and a right circular cylinder. Pictures of each are provided. Formulas are provided.

Use this online calculator to calculate the volume of geometric solids including a capsule, cone, frustum, cube, cylinder, hemisphere, pyramid, rectangular prism, sphere, and spherical cap.

This online calculator will find the area, circumference, and radii of an annulus. With any 2 known variables, you can calculate the other 5 unknowns.