[Free Registration/Login may be required to access all resource tools.] Derivation of double angle identities for sine, cosine, and tangent.

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...

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

Resource provides trigonometry formulas for unit circle, reciprocal identities, ratio identities, Pythagorean identities, sum and difference formulas, and double-angle formulas.

The Northeast Parallel Architectures Center, Syracuse University, provides a review and tutorial site on trigonometry. The information is in-depth and can be accessed by clicking on the various links in the outline.

Provides trigonometric identities, which include fundamental identities, even-odd identities, addition formulas, double-angle formulas, subtraction formulas, product-sum formulas, and identities for sin squared and cos squared.

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...

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.

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.

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 MathWords.com site lists the equations for all of the trigonometric identities.