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law of cosines
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law of cosines

mathematics
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Also known as: cosines, law of
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On the Web:
Academia - Geometry of the Law of Cosines (PDF) (May 04, 2025)

law of cosines, Generalization of the Pythagorean theorem relating the lengths of the sides of any triangle. If a, b, and c are the lengths of the sides and C is the angle opposite side c, then c2 = a2 + b2 − 2ab cos C.

This article was most recently revised and updated by William L. Hosch.