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
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cos(α) + cos(β) = 2 cos
cos
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sin(α) - sin(β) = 2 cos
sin
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cos(α) - cos(β) = - 2 sin
sin
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