A basic set-up leads to a surprisingly complex analysis in this variation on the question of surrounding a central circle with a ring of touching circles. Useful for putting trigonometric functions in a physical context, as well as...

Part of Eric Weisstein's comprehensive math site, this page deals with double-angle formulas. This site includes traditional trigonomic double-angle functions as well as hyperbolic trigonometric function. Includes links to related terms...

Twenty-two problems present a variety of practice working with double-angle and half-angle formulas. They are given with each step to the solution cleverly revealed one at a time. You can work each step of the problem then click the...

Double angles and half angles are explained through step by step examples. The steps are clear and easy to follow.

Students learn about the double and half angle formulas. Definitions and formulas are included.

This tutorial introduces the double-angle and half-angle formulas for sine, cosine, and tangent, and gives sample application and proof exercises. Assumes knowledge of the sum and difference formulas.

The University of Saskatchewan provides an explanation of trigonometric identities, including the reciprocal identities, the addition and subtraction formulas with sine and cosine, and the double angle formulas. There are links to...

At this site from eFunda you can scroll to the middle of the page for a listing of multiple angle formulas for cos, sin, and tan.

This lesson is the main SOS Math page for trigonometry. Surf the lesson to find most any trigonometric identity, formula, and many forms of help in the area of trigonometry.

Faced with a large number of trigonometric identities, students tend to try to memorize them all. This site the emphasis is on understanding how the functions work and on memorizing only about a half dozen of them - all the others work...

This tutorial highlights the numerous trigonometric identites (but does not define the basic trigonometric functions).

This resource clearly and thoroughly explains the many types of trigonometric identities. There are example problems solved, problems for the student to attempt, and answers to the student problems.