University of Saskatchewan (Canada)
University of Saskatchewan: Trigonometric Identities
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...
CK-12 Foundation
Ck 12: Geometry: Inverse Trigonometric Ratios
[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.
Purple Math
Purplemath: Trigonometric Identities
Lists the basic trigonometric identities, and specifies the set of trig identities to keep track of, as being the most useful ones for calculus.
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: 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.
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.
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.
University of Vienna (Austria)
Univ of Vienna: Trigonometric Functions
An interactive tool to discover how the trig functions came to be. Applets are used in this interactive learning tool. Examples exercises are also given.
Illustrative Mathematics
Illustrative Mathematics: G Srt Defining Trigonometric Ratios
The purpose of this task is to use the notion of similarity to define the sine and cosine of an acute angle. Aligns with G-SRT.C.6.
Homeschool Math
Homeschool Math: Introduction to Sine
This is an introductory lesson about the trigonometric function sine. Students will study several similar right triangles and the ratio of certain two sides in them.
Oswego City School District
Regents Prep: Applications of Trigonometric Graphs
Students can use this site to practice questions dealing with trigonometric graphs. Students are challenged with multiple real-world problems and after solving those problems they can check their solution online.
Varsity Tutors
Varsity Tutors: Hotmath: Practice Problems: Trigonometric Functions
Hotmath provides 24 practice problems relating to trigonometric functions. Each of the practice problems include a step-by-step guide for solving their function.
Khan Academy
Khan Academy: Trigonometry: Evaluate Inverse Trig Functions
Given a sine, cosine, or tangent value, find the principle angle that has this value. In other words, find the arcsine, arccosine, or arctangent of that value. Students receive immediate feedback and have the opportunity to try questions...
Other
Chat: Inverse Trig Functions [Pdf]
This site is a presentation that discusses how to graph inverse trigonometric functions. Topics included on the presentation are inverse sine, cosine and tangent functions.
Purple Math
Purplemath: Inverses of Trigonometric Ratios
You know that you can take side lengths and find trig ratios, and you know you can find trig ratios (in your calculator) for angles. What is missing is a way to go from the ratios back to the original angles. And that is what "inverse...
Wikimedia
Wikipedia: Trigonometric Function
This page from Wikipedia, a free and open-source encyclopedia, covers how to solve a variety of trigonometric equations, most of which involve substitution with a trigonometric identity. The identities themselves are not covered, but...
Varsity Tutors
Varsity Tutors: Hotmath: Practice Problems: Trigonometric Ratios
Sixteen problems cover a variety of topic of trigonometric ratios. 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 Solution" button to check each...
University of Vienna (Austria)
Trigonometry: Law of Sines
This is demonstration of how the law of sines works. It uses Java applets to manipulate the triangle and allows the user to explore what happens to the values of the triangle as the sides are changed.
Cuemath
Cuemath: Sine Function
A comprehensive guide for learning all about the sine function, unit circle and angles, how to use them, and their various applications. Check out the solved examples and practice questions for better understanding.
Cuemath
Cuemath: Sine Law
This comprehensive guide explores the topic of sine law, by finding answers to questions like what is the law of sines, what are the applications of sine law, and proof of the sine law. Includes solved examples and practice questions.
Other
Karl's Calculus Tutor: Trigonometric Functions
Great application of trig and introduction to the trig functions. Also found here are the Law of Sines and Law of Cosines as well as other trig topics to review.
CK-12 Foundation
Ck 12: Trigonometry: Trigonometric Identities and Equations
[Free Registration/Login may be required to access all resource tools.] Describe general forms and graphs for cosine and sine equations.
Lawrence Hall of Science
The Math Page: An Approach to Calculus: Derivatives of Trig. Functions
Here is a site that clearly and thoroughly explains how to find the derivative of each of the six trigonometric functions. There are example problems solved, problems for the student to attempt, and answers to the student problems. Point...
Khan Academy
Khan Academy: Trigonometric Ratios in Right Triangles
Given the side lengths of a right triangle, find the sine, cosine, or tangent of one of the acute angles. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.