# parallelogram law

###### Theorem 1

In an inner product space^{} (http://planetmath.org/InnerProductSpace), let $x$ and $y$ be vectors. Then

$${\parallel x+y\parallel}^{2}+{\parallel x-y\parallel}^{2}=2{\parallel x\parallel}^{2}+2{\parallel y\parallel}^{2}.$$ |

Title | parallelogram law^{} |
---|---|

Canonical name | ParallelogramLaw1 |

Date of creation | 2013-03-22 16:08:02 |

Last modified on | 2013-03-22 16:08:02 |

Owner | Mathprof (13753) |

Last modified by | Mathprof (13753) |

Numerical id | 9 |

Author | Mathprof (13753) |

Entry type | Theorem |

Classification | msc 46C05 |

Related topic | ParallelogramLaw |

Related topic | GeneralizationOfTheParallelogramLaw |