A | B |

coordinate plane | A number plane formed by two perpendicular number lines that intersect a their zero points |

x-axis | The horizontal number line in a coordinate plane |

y-axis | The vertical number line in a coordinate plane |

origin | The intersection of the x-axis and the y-axis and the coordinates are (0,0) |

quadrants | The four regions into which the x and y axes separate a plane |

x-coordinate | The first component x, in an ordered pair |

y-coordinate | The second component y, in an ordered pair |

ordered pair | Used to locate points in a coordinate plane and are written in the form (x,y) |

point | A basic undefined term in geometry that has no dimension and is represented by a dot |

line | A basic undefined term in geometry that extends indefinitely in opposite directions, has no thickness and is represented by a line with arrows at each end |

plane | A basic undefined term in geometry that extends in all directions, has no thickness and is represented by a flat surface |

collinear points | Points that lie on the same line |

coplanar points | Points that lie on the same plane |

midpoint | A point on a segment that separates the segment into two equal segments |

segment bisector | A segment, line, or plane that separates a segment into two equal segments and |

congruent segments | Segments that are equal in measure |

ray | A straight set of points that begins with one endpoint and extends indefinitely in one direction |

opposite rays | Two rays that have a common endpoint and extend in opposite directions |

angle | Two noncollinear rays with a common endpoint |

congruent angles | Angles that are equal in measure |

angle bisector | A ray that separates an angle into two equal angles |

protractor | An instrument used to measure angles |

acute angle | An angle whose measure is less than 90 degrees |

right angle | An angle whose measure is 90 degrees |

obtuse angle | An angle whose measure is greater than 90 degrees and less than 180 degrees |

straight angle | An angle who measure is 180 degrees |

adjacent angles | Two coplanar angles that have the same endpoint, a common side, and no interior points in common |

vertical angles | A pair of angles formed by two intersecting lines such that the sides of one angle are opposite ray of the sides of the other angle |

complementary angles | Two angles whose sum is 90 degrees |

supplementary angles | Two angles whose sum is 180 degrees |

linear pair of angles | Two adjacent angles whose sum is 180 degrees |