Windstream
Ojk World of Math: Relationships Between the Functions
This tutorial discusses relationships among all the trig identities. Examples are given on how to apply them to simplify trig expressions and prove identities.
Windstream
Ojk's Precalculus Study Page: Sum and Difference Formulas for Tangent
This tutorial introduces the sum and differnce formulas for tangent, and gives several examples of problems to be solved as well as proving other identities. Assumes knowledge of the sum and difference formulas for sine and cosine.
Varsity Tutors
Varsity Tutors: Hotmath: Practice Problems: Fundamental Trigonometric Identities
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...
Mathematics Archives
Math Archives: Visual Calculus: 47 Trig Identities!
This makes for a great handout for learners and teachers, alike! A comprehensive list of 47 commonly-used trig identities.
Windstream
Ojk's Precalculus Study Page: Area of a Triangle
An introduction to finding the area of a triangle using the sine function. Includes several pictures and examples.
Oswego City School District
Regents Exam Prep Center: Pythagorean Identities
The mathematics session investigates Pythagorean identities. The tutorial consists of class notes, calculator tips, examples, and practice problems with solutions. The teacher resource includes a worksheet that verifies a Pythagorean...
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
Charles Sturt University: Mathematics
The Univerisity of Charles Sturt provides math help in various areas including trigonometry. Site includes copies of past exams with solutions.
Clark University
Clark University: Dave's Short Trig Course: Summary of Trig 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.
CK-12 Foundation
Ck 12: Trigonometry: Double Angle Identities
[Free Registration/Login may be required to access all resource tools.] Derivation of double angle identities for sine, cosine, and tangent.
Khan Academy
Khan Academy: Find Trig Values Using Angle Addition Identities
Find the trigonometric values of various angles that (while they are not special angles) can be expressed as the sum or difference of special angles. Students receive immediate feedback and have the opportunity to try questions...
Cool Math
Coolmath: Pre Calculus Other Identities to Know
One page reference sheet of a quick recall of the Trig Identities.
CK-12 Foundation
Ck 12: Trigonometry: Trigonometry in Terms of Algebra
[Free Registration/Login may be required to access all resource tools.] Define trigonometric relationships with algebraic ratios.
Wolfram Research
Wolfram Math World: Trigonometry
This site provides a good definition of trigonometry. Includes many links to key terms and many more to related terms. This site may be used as a refresher for students who have finished the course, or students currently studying the...
Other
Technical Tutoring: Trig Identities
This resource is a quick review of the functions and identities in trigonometry.
Math2
Math2.org: Trigonometric Identities
This personal site is a listing of numerous trig identities. A great reference site.