A | B |

point | an exact location |

line | set of points that extends in opposite directions |

line segment | part of a line with two endpoints |

ray | part of a line with one endpoint |

angle | formed by two rays with a common endpoint |

vertex | the common endpoint of an angle |

right angle | angle that measures exactly 90 |

acute angle | has a measure of less than 90 |

obtuse angle | has a measure of more than 90 |

polygon | a closed plane figure made of line segments |

congruent | the same |

scalene triangle | triangle with no congruent sides |

isosceles triangle | triangle with two congruent sides |

equilateral triangle | triangle with all congruent sides |

perimeter | distance around a polygon |

chord | a line segment with its endpoints on the circle |

diameter | chord that passes through the center |

radius | line segment with an endpoint on circle & the other at center |

circumference | the distance around a circle |

parallel lines | lines that never meet |