A | B |

line segment | line with two endpoints |

ray | line that goes forever in one direction |

line | goes forever in two directions |

vertex | point where two lines meet |

acute angle | angle that has less than ninety degrees |

obtuse angle | angle that has more than ninety degrees |

right angle | angle that has exactly ninety degrees |

intersecting lines | lines that cross |

perpendicular lines | 2 lines that form a ninety degree angle |

parallel lines | 2 lines going in the same direction that never meet |

rectangle | plane figure with four right angles |

square | a plane figure with four equal sides |

triangle | geometric shape with three sides and three angles |

hexagon | polygon with six sides |

octagon | polygon with eight sides |

pentagon | polygon with five sides |

equilateral triangle | triangle with three equal sides |

isosceles triangle | triangle with at least two equal sides |

scalene triangle | triangle with no equal sides |

circumference | distance around a circle |