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# Geometry Terms

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

Point | No dimension, represents a precise location, symbolized with a dot and a capital letter. |

Line | One dimension (length). A straight path that extends infinitely in both directions. Two points determine a line. |

Segment | A part of a line between two endpoints. A finite length. |

Plane | A two dimensional (length and width) surface that extends infinitely in all directions. 3 non-collinear points determine a plane. |

Collinear | Three or more points on the same line. Co (together) Linear (line). |

Non-Collinear | Three or more points that are NOT on the same line. You know that 3 points are non collinear when you cannot draw one line that contains all three of those points. |

Coplanar | Points that lie on the same plane. |

Compass | Geometric tool used to draw a circle or part of a circle known as an arc. |

Straightedge | A tool used to draw straight lines. |

Congruent | Identical. Exactly the same shape and same size. |

Distance | The length of the segment between two points. |

Intersection | A point or set of points common to two or more geometric figures. The intersection of two lines is a point. The intersection of two planes is a line. |

Linear Pair | A pair of angles (two) that form a straight line. These are adjacent and add up to 180 degrees. |

Adjacent | Next to one another. Two angles are adjacent when they share a common vertex and a common side. |

Vertex | A common endpoint. The vertex of an angle is where the two sides of the angle converge or meet. |

Midpoint | The point exactly halfway between the endpoints of a segment. |

Angle | Two rays with a common vertex form an angle measured in degrees. |

Acute Angle | An angle that measures between 0 and 90 degrees. |

Obtuse Angle | An angle that measures between 90 and 180 degrees. |

Straight Angle | An angle that measures exactly 180 degrees. |

Construction Mark | A mark created using a compass. An arc is another name for a construction mark. |

Radius | Constant distance from the center of a circle to a point on the circle. |

Right Angle | An angle that measures exactly 90 degrees. |

Supplementary Angles | Two angles whose sum is 180 degrees. |

Complementary Angles | Two angles whose sum is 90 degrees. |

Proof | A logical argument in which each statement you make is supported by a reason that is accepted as true. |

Parallel Lines | Two lines that never intersect. There is always 180 degrees between them. |

Perpendicular | Forms a right angle. |

Equilateral | Having equal side lengths. |

Equiangular | Having equal angles. |

Right Triangle | A triangle that contains a right angle |

Triangle | 3 sided Polygon. Interior angles always sum to 180 degrees. |

Isosceles Triangle | Triangle with two congruent Legs and two congruent base angles. |

Equilateral Triangle | Triangle with 3 congruent sides and angles. |

Corresponding parts | Matching parts of congruent figures. |

Pythagorean Theorem | A group of three whole numbers that satisfies the equation a^2 + b^2 = c^2, where c is the greatest number. |

Hypotenuse | The largest side of a right triangle. This side is directly 0pposite the right angle. |

Equidistant | The same distance. |

Perpendicular Bisector | A line that is perpendicular (forms right angle) and passes through the midpoint of a segment. Any point on a perpendicular bisector is always equidistant from the two points in which is being bisected. |

Bisector | Cuts exactly into two congruent parts. |

Angle Addition | Part + Part = Whole. The Whole is the sum of its parts. Two adjacent angles that combine to form a larger angle. |

Segment Addition | Part + Part = Whole. The Whole is the sum of its parts. Two segments that combine to form a larger segment. |