A | B |

CIRCLE | The set of all points in a plane at a given distance from a given point |

RADIUS | The distance from the center of the circle |

CENTER | The given point |

CONGRUENT CIRCLES | 2 circles with equal radii |

CONCENTRIC CIRCLES | 2 circles with the same center |

CHORD | SEGMENT with both endpoints on the circle |

DIAMETER | CHORD through the center of the circle |

SECANT | LINE that intersects the circle in 2 places |

TANGENT | LINE that touches the circle in 1 point |

INSCRIBED ANGLE | Angle with the vertex ON the circle |

CENTRAL ANGLE | Angle with the vertex AT THE CENTER of the circle |

ARC OF A CIRCLE | Part of the circle |

ENDPOINTS OF THE ARC | Where the chords intersect the circle |

SEMICIRCLE | 1/2 of the circle |

MINOR ARC | Less than 1/2 of the circle |

MAJOR ARC | More than 1/2 of the circle |

TANGENT CIRCLE | 2 circles that intersect in exactly 1 point |

CIRCUMFERENCE | Distance around the circle |

LENGTH OF AN ARC | Part of the circumference from endpoint to endpoint |