Lists the basic trigonometric identities, and specifies the set of trig identities to keep track of, as being the most useful ones for calculus.

One page reference sheet of a quick recall of the Pythagorean Identities.

Demonstrates how to evaluate trigonometric functions by using trig identities.

A comprehensive guide for learning all about the basics of trigonometry, the various identities-formulas of trigonometry, solved examples, and practice questions.

This section explores the Pythagorean Identity and how it applies to right triangles set inside unit circles, in terms of sine, cosine, and tangent functions.

Using similar triangles, a relationship is established between the six trigonometric functions of an angle and simple line segments. These relationships are then confirmed using line segment measurement capabilities of the graphing...

Here is a site that clearly and thoroughly explains the trigonometric functions of acute angles within a right triangle. There are example problems solved, problems for the student to attempt, and answers to the student problems. Point...

A collection of video lessons with example problems and solutions to help students learn how to extend polynomial identities to the complex numbers. Includes interactive widget for working on the modeled problems or trying your own.

This site contains graphs of the exponential function, identities relevant to the function, and the Maclaurin series for this function.

In this TI InterActive! activity, students study the phases of the moon, plot the fraction of the moon showing each day in a month, and fit the data with an appropriate trigonometric function.

This lesson encourages students to explore the phenomenon of identical twins, with emphasis on behavioral as well as genetic aspects. Teachers will appreciate extension activities, suggested readings, and links in addition to lesson plan...

Online notes with examples and solutions.

[Free Registration/Login may be required to access all resource tools.] Advanced applications of trigonometric identities.

This section introduces radians an alternative to degrees as a way to measure the rotation around a circle. It also begins to draw connections between radians and trigonometric identities.

Learners use the given figure and a straightedge to approximate the values of each trigonometric function. The figure is available in PDF format.

Learners use the given figure and a straightedge to approximate the values of each trigonometric function. The figure is available in PDF format.

In this lesson, students talk about dressing up and taking on identities that are similar to or different from them. They are then introduced to the idea of avatars as a kind of "dressing up" inside video games and consider the ways in...

A lesson plan where students will interpret the trigonometric functions in terms of the unit circle, graph a sinusoidal function, and use a sinusoidal function to make interpretations in a modeling context.

Given the sine (or cosine) of an angle, find its cosine (or sine) using the Pythagorean identity. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.

Here is a site that clearly and thoroughly explains the trigonometry of a right triangle, including finding the values of all six trig functions given a single value. There are example problems solved, problems for the student to...

An introduction to solving acute and obtuse triangles by using the law of cosines, including a derivation of the formula. Includes several pistures and examples.

[Free Registration/Login may be required to access all resource tools.] Finding the value for trigonometric functions for angles exceeding 360 degrees.

[Free Registration/Login may be required to access all resource tools.] Learn how to define trigonometric functions of angles with negative values.

[Free Registration/Login may be required to access all resource tools.] Determine if three side lengths make a right triangle, and given the length of its legs, find the length of a right triangle's hypotenuse.