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# Module Geometry

### All important words in geometry

Question | Answer |
---|---|

Point | A point is a location with no size or shape |

Line | A line is made up of points with no thickness or width |

Line Segment | A measurable part of a line consisting of 2 endpoints |

Ray | Part of a line that extends indefinitely in one direction |

Plane | A plane is a flat surface made up of points and expands indefinitely in all directions |

Collinear | Points that lie on the same line -- non-collinear; points that don't lie on the same lines |

Coplanar | Points that lie on the same plane -- non-coplanar; points that don't lie on the same plane |

Congruent Segments | If 2 segments have the same length then they are congruent |

Segment Addition Postulate | If A, B, and C are collinear points and B is between A and C, then Ab + BC = AC |

Distance Formula | The formula used to find the distance between the points on a coordinate plane d = square root of (x2 - x1)^2 + (y2 - y1)^2 |

Midpoint formula | The formula used to mind the midpoint between 2 points M = (x1+x2/2, y1 +y2/2) |

Segment Bisector | A segment, line, ray; plane that intersects a segment at the midpoint |

Perpendicular | Two lines that intersect at a 90 degree angle (right angle) symbol is an upside down T |

Perpendicular Bisector | A line, segment, or ray perpendicular to a segment at its midpoint |

Parallel Lines | Two lines that never intersect symbol: || |

Angle | Two rays with a common endpoint |

Vertex | The common endpoint of an angle |

Right angle | An angle with a measure of 90 degrees |

Acute angle | An angle with a measure less than 90 degrees |

Obtuse angle | An angle with a measure greater than 90 degrees |

Straight angle | An angle with a measure of 180 degrees |

Congruent angles | Two angles that have the same measure are congruent |

Adjacent angles | Two angles that share a vertex and a side |

Angle addition postulate | If angle ABD and angle DBC are adjacent, then measure of angle ABD + measure of angle DBC = measure of angle ABC |

Angle bisector | A line or ray that divides an angle into 2 "=" points |

Vertical angles | Two angles directly across from each other on intersecting lines *always congruent* |

Complementary angles | 2 angles with measures that sum to 90 degrees "don't have to be adjacent* |

Supplementary angles | 2 angles with measures that sum to 180 degrees "don't have to be adjacent* |

Linear pair | Adjacent angles that form a straight line, they are supplementary |

An angle is formed by 2 ___ with a common endpoint | rays |

This common endpoint is called the ___ | vertex |

Name an angle using ___ letters | 3 |

A ray that divides an angle into ___ _____ ____ | 2 congruent angles |

Two lines that _____ at a _____ ______ | intersect right angle |

A line, segment, or ray _______ to a segment is its ______ | perpendicular midpoint |