Texas Instruments
Texas Instruments: Learning Pre Calculus With the Ti 89
See examples of how to use the TI-89 in Pre-Calculus. Example topics include equations with radicals, trigonometric identities, composition of functions, and inverse functions.
Analyze Math
Analyze Math: Trigonometric Identities
Learners explore trigonometric identities. Definitions of the Pythagorean, reciprocal, tangent, and negative identities are included.
Math Medics
S.o.s. Math: Trigonometry: The Addition Formulas
This math lesson contains a list of trigonometric addition formulas. Includes example problems involving these formulas along with solutions.
Wolfram Research
Wolfram Math World: Inverse Trigonometric Functions
A site on inverse trigonometric functions. Contains a definition, a chart showing functions and their domains, formulas, and many links.
University of Saskatchewan (Canada)
Exercises in Math Readiness for University Study: Trig
Read a lesson, look at examples, and try easy, medium, and advanced problems from a variety of trigonometry topics: radian measure of angles, trigonometric functions, trigonometric identities, and modeling with trigonometric functions.
Other
Sierra College: Trigonometric Identities
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.
Other
Brown Math: Remembering 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...
Clark University
Clark University: Dave's Short Trig Course
This Clark University trigonometry tutorial site features questions and answers about what students can learn from trigonometry.
Math Planet
Math Planet: Algebra 2: Trigonometry: Trigonometric Identities
Provides an explanation, examples, and a video lesson all related to trigonometric identities. [2:31]
Wolfram Research
Wolfram Math World: Trigonometric Addition Formulas
This tutorial offers formulas and explanations on trigonometric addition formulas and features an easy way to remember the sine and cosine addition formulas using matrices.
Wolfram Research
Wolfram Math World: Double Angle Formulas
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...
Wolfram Research
Wolfram Math World: Half Angle Formulas
This page, from Eric Weisstein's comprehensive Math World site, offers information on half-angle formulas. The site includes traditional trigonometric fuctions half-angle formulas as well as hyperbolic half-angle formulas. Includes links...
Windstream
Ojk's Precalculus Study Page: Sum and Difference Formulas for Sine and Cosine
An introduction to trigonometric identities, beginning with the sum and difference formulas. Some of the formulas are proven, some are left to the reader. Includes several examples and pictures.
Math Medics
S.o.s. Math: Table of Trigonometric Identities
This tutorial highlights the numerous trigonometric identites (but does not define the basic trigonometric functions).
Math Words
Math words.com: Trig Identities
This MathWords.com site lists the equations for all of the trigonometric identities.
McGraw Hill
Glencoe: Online Study Tools: Quiz on Basic Trigonometric Identities
Students show comprehension of advanced mathematical concepts in Trigonometry. The online quiz assesses the scholars on basic trigonometric identities.
McGraw Hill
Glencoe: Online Study Tools: Quiz on Verifying Trigonometric Identities
Students show understanding of advanced mathematical concepts in Trigonometry. The online quiz tests the scholars on verifying trigonometric identities.
CK-12 Foundation
Ck 12: Trigonometry: Proofs of Trigonometric Identities
[Free Registration/Login may be required to access all resource tools.] Simplifying trigonometric expressions using identities
CK-12 Foundation
Ck 12: Trigonometry: Proofs of Trigonometric Identities
[Free Registration/Login may be required to access all resource tools.] This lesson uses trigonometric identities to prove other identities.
CK-12 Foundation
Ck 12: Trigonometry: Quotient Identities
[Free Registration/Login may be required to access all resource tools.] Illustrates identities found from dividing two trigonometric functions.
CK-12 Foundation
Ck 12: Trigonometry: Triple Angle Formulas and Linear Combinations
[Free Registration/Login may be required to access all resource tools.] Advanced applications of trigonometric identities.
Math Is Fun
Math Is Fun: Trigonometric Identities
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.
Varsity Tutors
Varsity Tutors: Hotmath: Practice Problems: Sum and Difference Formulas
Twenty problems are presented for practice working with sum and difference formulas for sine, cosine, and tangent.
CK-12 Foundation
Ck 12: Trigonometry: Cofunction Identities and Reflection
[Free Registration/Login may be required to access all resource tools.] Find different trigonometric functions that have the same values for a given angle.