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...

Given problem situations involving similar figures, the student will apply and justify triangle similarity relationships such as trigonometric ratios.

This list of trigonometric identities includes the factoring formulas near the bottom. A great tool for reference.

A collection of lessons and practice exercises on trigonometric ratios. Students will learn how to solve for an angle and for a side, and to apply trigonometry in setting up and solving word problems.

This site reviews basic information on inverse functions and inverse notation. Graphs of inverse trig functions are shared and discussed.

[Free Registration/Login may be required to access all resource tools.] Use a calculator to find trigonometric ratios.

[Free Registration/Login may be required to access all resource tools.] This concept teaches students to find trigonometric ratios with a calculator in order to find missing sides of right triangles.

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.

[Free Registration/Login may be required to access all resource tools.] This lesson uses trigonometric identities to prove other identities.

[Free Registration/Login may be required to access all resource tools.] This concept teaches students to use inverse trigonometric ratios to solve for missing angles in right triangles.

This makes for a great handout for students and teachers, alike! A comprehensive list of 47 commonly-used trig identities.

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...

Students show comprehension of advanced mathematical concepts in Trigonometry. The online quiz assesses the scholars on basic trigonometric identities.

The mathematics tutorial verifies trigonometric identities. The tutorial consists of several examples with detailed solutions.

Twenty problems present a variety of practice working with fundamental trigonometric identities. 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 "View...

[Free Registration/Login may be required to access all resource tools.] How to Compose a trigonometric function.

A good introduction to trigonometric identities, equations that are always true for a right triangle and require knowledge of the functions sine, cosine, and tangent.

[Free Registration/Login may be required to access all resource tools.] Simplifying trigonometric expressions using identities

This Clark University page is an excellent reference page for trig identities. It is a little difficult to read so take your time with the formulas. If you remember soh - cah - toa, the other formulas are right here.

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

[Free Registration/Login may be required to access all resource tools.] Use the inverse trigonometric ratios.

Learners explore trigonometric identities. Definitions of the Pythagorean, reciprocal, tangent, and negative identities are included.

[Free Registration/Login may be required to access all resource tools.] On this site students learn about the composition of inverse trigonometric functions. Students read about inverse reciprocal functions, watch a video about the topic...

Given eight trigonometric functions containing absolute value elements, choose whether each is differentiable or non-differentiable. At the conclusion of the exercises, the site returns a score which helps judge understanding of the topic.