Trigonify

Product to Sum

sin · cos

sin⁡αcos⁡β=12[sin⁡(α+β)+sin⁡(α−β)]\sin\alpha \cos\beta = \tfrac{1}{2}[\sin(\alpha+\beta) + \sin(\alpha-\beta)]

Related Product to Sum identities

cos · cossin · sin

Study this and 44 more identities in the Trigonify workspace — an interactive unit circle, a step-by-step triangle solver, quizzes, and a practice problem bank.