Videos and lessons to help High School students learn how to prove the addition and
subtraction formulas for sine, cosine, and tangent and use them to solve problems.

Trig Identities Sine Addition and Subtraction

Proof of the Sine angle sum/difference identity.

Trig Identities Cosine Addition and Subtraction

Proof of the Cosine angle sum/difference identity.

Trig Identities Tangent and using the identities

Proof of the Tangent angle sum/difference identity.

Trig Identities

The fundamental trig identities and some strategies for solving beginning general trigonometric identities.

Sum and Difference Identities for Sine

Use the sum and difference sine identity to determine function values.

Sum and Difference Identities for Cosine

Use the sum and difference cosine identity to determine function values.

Sum and Difference Identities for Tangent

Use the sum and difference tangent identity to determine function values.

Cosine addition identity example.

Proof of the Sine angle sum/difference identity.

Trig Identities Cosine Addition and Subtraction

Proof of the Cosine angle sum/difference identity.

Trig Identities Tangent and using the identities

Proof of the Tangent angle sum/difference identity.

Trig Identities

The fundamental trig identities and some strategies for solving beginning general trigonometric identities.

Sum and Difference Identities for Sine

Use the sum and difference sine identity to determine function values.

Sum and Difference Identities for Cosine

Use the sum and difference cosine identity to determine function values.

Sum and Difference Identities for Tangent

Use the sum and difference tangent identity to determine function values.

Cosine addition identity example.

Try the free Mathway calculator and
problem solver below to practice various math topics. Try the given examples, or type in your own
problem and check your answer with the step-by-step explanations.

We welcome your feedback, comments and questions about this site or page. Please submit your feedback or enquiries via our Feedback page.