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# Geometry 8.1

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

Endpoints | 2 points on any line |

Ray | the subset of a line that contains a specific point (the endpoint) and all the points on the line that are on the same side of that point |

Intersect | wherever 2 lines meet or where 2 lines have a point in common |

Perpendicular | where 2 intersecting lines form right angles |

Concurrent | where 3 or more lines intersect at a single point |

Parallel | where 2 lines lie in the same plane and never intersect |

Complementary Angles | the sum of the measure of 2 angles equals 90 degrees |

Supplementary Angles | the sum of the measure of 2 angles equals 180 degrees |

Hand-Eye Coordination | One aspect of spatial thinking. The ability of the vision system to coordinate the information received through the eyes to control, guide, and direct the hands in the accomplishment of a given task. |

Figure-Ground Perception | The ability to identify a figure against a complex background. |

Perceptual Constancy | The ability to recognize figures and objects when they are not in their familiar orientation. |

Visual Discrimination | The ability to find similarities and differences between or among objects. |

Visual Memory | Deals with the person's ability to describe or draw accurately, an object that is no longer in view. |

Point | Geometrically, has no dimension (length or width), but it does have a location. |

Right Angle | An angle whose measurement is 90 degrees. |

Acute Angle | An angle whose measure is less than 90 degrees. |

Obtuse Angle | An angle whose measure is greater than 90 degrees but less than 180 degrees. |

Line | straight and extends infinitely in two directions |

Plane | A flat surface that extends infinitely in all directions. |

Collinear Points | Points that lie on the same line. Any two points are collinear. |

Noncollinear Points | three (or more) points that do not lie on a single line |

Coplanar Points | two or more points that lie on a single line |

Line Segment | A subset of a line that contains two points of the line and all points in between those points. |

Straight | An angle whose measure is 180 degrees. |

Reflex | An angle whose measure is greater than 180 degrees but less than 360 degrees. |

Skew | Two lines that do not intersect because they do not lie in the same plane. |

Angle | The union of two rays that have a common endpoint |

Vertex | The common endpoint of two rays. |

Side | Each of the rays of the angle |

Interior | The angle formed inside of a shape |

Exterior | |

Vertical angles | When two lines intersect, four angles are formed. The angle that are opposite of each other are vertical angles. |