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# Geometry Unit

### Angles, Triangles

Term | Definition |
---|---|

ray | shared by adjacent angles |

sum | the answer to an addition problem |

intersecting lines | lines that cross at a point |

vertical angles | angles which are formed by intersecting lines and have equal measures |

adjacent angles | angles that are next to each other |

supplementary angles | angles whose measures have a sum of 180 degrees |

complementary angles | angles whose measures have a sum of 90 degrees |

acute angle | has a measure less than 90 degrees |

obtuse angle | has a measure more than 90 degrees, but less than 180 degrees |

right angle | has a measure of exactly 90 degrees |

acute triangle | a three sided shape with all angles measuring less than 90 degrees |

right triangle | a three sided shape with one angle measuring exactly 90 degrees |

obtuse triangle | a three sided shape with one angle measuring greater than 90 degrees |

isosceles triangle | a three sided shape with two congruent sides |

equilateral triangle | a three sided shape with all congruent sides |

scalene triangle | a three sided shape with all sides measuring different lengths |

triangle inequality theorem | Helps us to know if three sides will form a triangle. The sum of the two smaller sides, must be greater than the largest side. |

No, 2 + 5 needs to be greater than the third side. | Will sides of 2, 5, and 7 form a triangle? |

No, 4 + 10 needs to be greater than the third side. | Will sides of 4, 15, and 10 form a triangle? |

Yes, 4 + 5 is greater than the third side. | Will sides of 4, 5, and 6 form a triangle? |

2<x<10 | If two sides of a triangle are 6 and 4, give the range of values for the third side. |

180 degrees | What is the sum of all the measures of the angles of a triangle? |

congruent | having exactly the same shape, size or measure |

5<x<11 | If two sides of a triangle are 8 and 3, give the range of values for the third side. |

15<x<55 | If two sides of a triangle are 20 and 35, give the range of values for the third side. |