# isosceles triangle

An *isosceles triangle ^{}* is a triangle with two congruent sides. The angles opposite these two sides are the base angles and the angle between those sides is the vertex angle of the triangle.

This definition implies that any equilateral triangle^{} is isosceles
too, but there are isosceles triangles that are not equilateral.

In any isosceles triangle, the angles opposite to the congruent sides are also congruent. In fact, this condition could be used to give an alternate definition of isosceles, since a triangle is isosceles if and only if it has two congruent angles.

In an equilateral triangle, the height (http://planetmath.org/BaseAndHeightOfTriangle), the median and the bisector^{} to
the third side are the same line.

Title | isosceles triangle |

Canonical name | IsoscelesTriangle |

Date of creation | 2013-03-22 11:44:12 |

Last modified on | 2013-03-22 11:44:12 |

Owner | drini (3) |

Last modified by | drini (3) |

Numerical id | 17 |

Author | drini (3) |

Entry type | Definition |

Classification | msc 51-00 |

Classification | msc 49J20 |

Classification | msc 49J30 |

Classification | msc 49-01 |

Synonym | isosceles |

Related topic | Triangle |

Related topic | RightTriangle |

Related topic | EquilateralTriangle |

Related topic | EquivalentConditionsForTriangles |

Related topic | EquiangularTriangle |

Related topic | RegularTriangle |

Defines | base angle |

Defines | vertex angle |