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# Unit 2 - Mr. Hunt

### 2D Geometry

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

side | line segment that make up a polygon |

angle | two rays or lines that share a common point or vertex |

congruent | equal in size or length |

parallel lines | two lines that would never intersect when headed in both directions forever |

perpendicular | two lines that intersect at a 90 degree angle |

straight angle | a 180 degree angle |

right angle | a 90 degree angle |

obtuse angle | an angle greater than 90 degrees |

acute angle | an angle less than 90 degrees |

vertical angles | the congruent opposite angles that are formed when two lines intersect |

adjacent angles | two angles that share a common side, line, or ray |

complimentary angles | two angles that sum to 90 degrees |

supplementary angles | two angles that sum to 180 degrees |

concave polygon | a shape or polygon that is curved inwards |

convex polygon | a shape or polygon that is curved outwards |

degree | a measure for angles |

exterior angles | the angle made outside of a shape |

interior angles | the angle made from the inside of a shape |

irregular polygon | a polygon where are all side and angles are not equal |

polygon | a many sided, closed figure |

protractor | a tool used for measuring and drawing angles |

regular polygon | a polygon with all sides equal in length and all angles equal in size |

rectangle | a quadrilateral where all angles are 90° and opposite sides are congruent |

reflectional symmetry | A type of symmetry where a line could be drawn and one half is a reflection of the other half |

rotation | a circular movement of a shape around a fixed point |

rotational symmetry | A type of symmetry where a shape can be rotated (less than a full turn) around a fixed point and remain the same |

tesselation | a pattern made of identical shapes |

transversal | a line that crosses at least two other lines |

triangle | a 3 sided polygon |

quadrilateral | a 4 sided polygon |

pentagon | a 5 sided polygon |

hexagon | a 6 sided polygon |

heptagon | a 7 sided polygon |

octagon | a 8 sided polygon |

nonagon | a 9 sided polygon |

decagon | a 10 sided polygon |

dodecagon | a 12 sided polygon |

rhombus | a 4 sided polygon where all sides are equal |

square | a 4 sided polygon where all sides are equal and all angles are 90° |

parallelogram | a 4 sided polygon with 2 pairs of parallel sides |

trapezoid | quadrilateral where only one pair of opposite sides are parallel. |

quadrants | a quarter of a circle made by two radiuses at a right angle |