MathLiveLaw of cosines
Relates the lengths of the three sides of any triangle to the cosine of one of its angles. It is used to find a missing side when two sides and the included angle are known, or a missing angle when all three sides are known.
c^2 = a^2 + b^2 - 2ab\cos CWhat the symbols mean
| length of the side opposite angle A | |
| length of the side opposite angle B | |
| length of the side opposite angle C | |
| angle opposite side c |
About this formula
- FieldMathematics
- TopicTrigonometry
- LevelHigh school
- Also calledcosine law, cosine formula, cosine rule, Al-Kashi theorem, generalized Pythagorean theorem, Al-Kashi Theorem
- SourceWikidata Q164321
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