A | B |

acute angle | An angle with a measure greater than zero degrees but less than 90 degrees. |

angle | wo rays with a common endpoint. |

bisect | To separate something into two congruent parts. |

complementary | Two angles whose measures have a sum of 90 degrees. |

congruent | Having the same measure. |

congruent figures | Figures that are the same shape and size. |

corresponding parts | The parts of congruent figures that match. |

degree | The most common unit of measure for angles. |

equilateral triangle | A triangle having all three sides congruent and all three angles congruent (all angles equal 60 degrees). |

heptagon | A polygon having seven sides. |

hexagon | A polygon having six sides. |

isosceles triangle | A triangle in which at least two sides are congruent. |

line of symmetry | A line that divides a figure into halves that are reflections of each other. |

line symmetry | Figures have this when two halves of the figure match. |

obtuse angle | An angle that measures greater than 90 degrees but less than 180 degrees. |

octagon | A polygon having eight sides. |

parallelogram | A quadrilateral that has both pairs of opposite sides congruent and parallel. |

pentagon | A polygon having five sides. |

perpendicular | Two line segments that intersect to form right angles. |

polygon | A simple closed figure in a plane formed by three or more line segments. |

quadrilateral | A polygon with four sides. |

rectangle | A quadrilateral with opposite sides congruent and parallel and all angles are right angles. |

regular polygon | A polygon having all sides congruent and all angles congruent. |

rhombus | A parallelogram with all sides congruent. |

right angle | An angle that measures exactly 90 degrees. |

rotational symmetry | A figure has this if it can be turned or rotated less than 360 degrees about a fixed point so that the figure looks exactly as it did before being turned. |

scalene triangle | A triangle in which no sides are congruent. |

side | A ray that is part of an angle. |

similar figures | Figures that have the same shape but different sizes. |

square | A parallelogram with all sides congruent, all angles are right angles,, and opposite sides are parallel. |

straight angle | An angle that measures exdactly 180 degrees. |

supplementary | Two angles whose measures have a sum of 180 degrees. |

triangle | A polygon having three sides. |

vertex | The common endpoint of the two rays that form an angle. |