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.
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.
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.
Analyze Math
Analyze Math: Trigonometry: Sum and Difference Formulas
Students explore trigonometric formulas. Definitions of the sum and difference formulas are included.
CK-12 Foundation
Ck 12: Trigonometry: Applications of Sum and Difference Formulas
[Free Registration/Login may be required to access all resource tools.] Solving equations and verifying identities with the sum and difference formulas.