# cosines law

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

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

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

Title | cosines law |

Canonical name | CosinesLaw |

Date of creation | 2013-03-22 11:42:35 |

Last modified on | 2013-03-22 11:42:35 |

Owner | drini (3) |

Last modified by | drini (3) |

Numerical id | 26 |

Author | drini (3) |

Entry type | Theorem |

Classification | msc 51M04 |

Classification | msc 05A15 |

Classification | msc 05A10 |

Classification | msc 05A16 |

Synonym | law of cosines |

Related topic | SinesLaw |

Related topic | PythagorasTheorem |

Related topic | DerivationOfCosinesLaw |

Related topic | CosinesLaw |

Related topic | StewartsTheorem |

Related topic | AlternativeProofOfTheSinesLaw |

Related topic | SinesLawProof |

Related topic | ProofOfStewartsTheorem |