Sum and Difference Formulas

The sine of the sum and difference of two angles is as follows:

sin(α+β)=sinα cosβ + cosα sinβ

sin(α−β)=sinα cosβ − cosα sinβ

The cosine of the sum and difference of two angles is as follows:

cos(α+β)=cosα cosβ − sinα sinβ

cos(α−β)=cosα cosβ + sinα sinβ

We can verify all the reference angles formulas using the sum and difference formulas.

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Practice: Answer the following exercises about sum and difference formulas.