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# cosines law

Cosines Law. Let $a$, $b$, $c$ be the sides of a triangle and $A$ the angle opposite to $a$. Then

$a^{2}=b^{2}+c^{2}-2bc\cos A.$ |

Remark. Cosines law is the generalised form of Pythagorean theorem, which latter concerns only the right triangles.

Keywords:

Cosine, Sine, Trigonometry, Triangle

Related:

SinesLaw, PythagorasTheorem, DerivationOfCosinesLaw, CosinesLaw, StewartsTheorem, AlternativeProofOfTheSinesLaw, SinesLawProof, ProofOfStewartsTheorem

Synonym:

law of cosines

Type of Math Object:

Theorem

Major Section:

Reference

Groups audience:

## Mathematics Subject Classification

51M04*no label found*05A15

*no label found*05A10

*no label found*05A16

*no label found*

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## Comments

## for a good laugh

check out version 1

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