CK-12 Foundation
Ck 12: Trigonometry: Secant, Cosecant, and Cotangent Functions
[Free Registration/Login may be required to access all resource tools.] This lesson covers secant, cosecant, and cotangent.
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.
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.
Math Is Fun
Math Is Fun: Introduction to Trigonometry
Students are introduced to concepts taught in trigonometry. The tutorial consists of notes and examples.
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...
Khan Academy
Khan Academy: Using the Trig Angle Addition Identities
Find the trig values of sums of angles whose individual trig values are known. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Analyze Math
Analyze Math: Verify Trigonometric Identities
The mathematics tutorial verifies trigonometric identities. The tutorial consists of several examples with detailed solutions.
Lawrence Hall of Science
The Math Page: Trigonometry: Trigonometric Identities
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.
Cool Math
Coolmath: The Pythagorean Identities
One page reference sheet of a quick recall of the Pythagorean Identities.
Cool Math
Coolmath: Pre Calculus Other Identities to Know
One page reference sheet of a quick recall of the Trig Identities.
Paul Dawkins
Paul's Online Notes: Trig Functions
In this section we will give a quick review of trig functions. We will cover the basic notation, relationship between the trig functions, the right triangle definition of the trig functions. We will also cover evaluation of trig...
Lawrence Hall of Science
The Math Page: Trigonometry
Concepts in Trigonometry are explained and illustrated here by a member of the math department at Borough of Manhattan Community College.
Illustrative Mathematics
Illustrative Mathematics: F Tf Trigonometric Ratios and the Pythagorean Theorem
The purpose of this task is to use the Pythagorean Theorem to establish a fundamental trigonometric identity for an acute angle. The reasoning behind this identity is then applied to calculate a cosine for a given obtuse angle. Aligns...
University of St. Andrews (UK)
University of St. Andrews: Trigonometric Functions
This site from the University of Saint Andrews provides an historical look at the origins of trig functions. This site ties together mathematics and history from Hipparchus to Ptolemy to Lambert.
Khan Academy
Khan Academy: Algebra Ii: Use the Pythagorean Identity
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.
CK-12 Foundation
Ck 12: Trigonometry: Cosine Sum and Difference Formulas
[Free Registration/Login may be required to access all resource tools.] Examples, videos, and practice problems covering cosine of a sum or difference related to a set of cosine and sine functions. Here you'll learn to rewrite cosine...
CK-12 Foundation
Ck 12: Exact Values for Inverse Sine, Cosine, and Tangent
[Free Registration/Login may be required to access all resource tools.] Find all angles on the unit circle matching exact trig ratios. Resource includes examples, videos, and practice problems.
CK-12 Foundation
Ck 12: Trigonometry: Composition of Trig Functions and Their Inverses
[Free Registration/Login may be required to access all resource tools.] How to Compose a trigonometric function.
CK-12 Foundation
Ck 12: Trigonometry: Simpler Form of Trigonometric Equations
[Free Registration/Login may be required to access all resource tools.] Simplify trigonometric expressions using identities.
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.
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.
Cool Math
Coolmath: The Pythagorean Identities
A resource describing Pythagorean Identities with visuals.
CK-12 Foundation
Ck 12: Algebra Ii: 4.1 Revisiting Right Triangle Trigonometry
Use this tutorial to revisit right triangle trigonometry.
CK-12 Foundation
Ck 12: Algebra Ii: 4.8 Pythagorean Identities
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.