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More Trigonometric Identities

Sums and Differences of Functions



The following formulas relate the sum of trigonometric functions of different angles to products of multiple angle functions. These identities are also useful for simplifying expressions.

sin(α) + sin(β) = 2 sin cos    

cos(α) + cos(β) = 2 cos cos    

sin(α) - sin(β) = 2 cos sin    

cos(α) - cos(β) = - 2 sin sin