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.

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