[<< wikibooks] High School Trigonometry/Sum and Difference Identities for Cosine
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{\displaystyle \cos {u\pm v}=\cos {u}\cos {v}\pm \sin {u}\sin {v}}

This material was adapted from the original CK-12 book that can be found here. This work is licensed under the Creative Commons Attribution-Share Alike 3.0 United States License