A | B |

Vertex | b.a point in a geometrical solid common to three or more sides.c.the intersection of two sides of a plane figure. |

interior angle | an angle formed by two sides of a simple polygon that share an endpoint, namely, the angle on the inner side of the polygon |

exterior angle | angle formed by one side of a simple polygon and a line extended from an adjacent side |

adjacent angles | two angles having the same vertex and having a common side between them |

complementary angles | Two angles whose sum is 90°. |

supplementary angle | Two angles whose sum is 180° |

perpendicular | meeting a given line or surface at right angles |

horizontal line | A line with the slope of 0. When graphing it is parallel to the x axis |

vertical line | A line with an undefined slope x/0. When graphing a vertical line it is parallel to the y axis |

intersect | Lines that have 1 or more points in common; those that cross |

bisect | to cut or divide into two equal parts |

alternate angles | two nonadjacent angles made by the crossing of two lines by a third line, both angles being either interior or exterior, and being on opposite sides of the third line |

straight angle | formed when the legs are pointing in exactly opposite directions; this forms a line (180 degrees) |

collinear | Passing through or lying on the same straight line |

coplanar | being or operating in the same plane |

congruent | similar; equal |

vertical angles | Two angles formed by two intersecting lines and lying on opposite sides of the point of intersection (they share a common vertex) |

acute angle | An angle measuring less than 90 degrees |

right angle | An angle measuring 90 degrees |

obtuse angles | An angle measuring more than 90 degrees but less than 180 degrees |

reflex angles | An angle measuring more than 180 degrees but less than 360 degrees |

coordinates | (x,y); points on a graph |