Shape | Term | Definition |

perpendicular line segments | Two line segments which cross to form 90 degree angles. | |

right angle | A 90 degree angle. | |

equilateral triangle | A triangle with all sides equal and all angles equal. | |

scalene triangle | A triangle having three unequal sides and angles. | |

vertex | The intersection point of two sides of a plane figure. | |

right triangle | A triangle with one internal angle equal to 90 degrees. | |

pentagon | A polygon with 5 sides and 5 angles. | |

square | A rectangle having all four sides of equal length. | |

intersecting line segments | Line segments that cross each other. | |

acute angle | An angle less than 90 degrees but greater than 0 degrees. | |

chord | The line segment between two points on a given curve. | |

radius | A straight line extending from the center of a circle or sphere to the circumference or surface. | |

line segment | One part of a line. | |

line | A continuous extent of length. | |

point | A position in space. | |

parallelogram | A quadrilateral having both pairs of opposite sides parallel to each other.(Note: squares and rectangles are also quadrilaterals.) | |

rectangle | A parallelogram having four right angles.(Note: a square is also a rectangle.) | |

rhombus | An equilateral parallelogram having oblique angles. | |

parallel line segments | Line segments that do not intersect. | |

quadrilateral | A polygon with four sides.(Note: squares, rectangles and trapezoids are also quadrilaterals.) | |

octagon | A polygon having eight angles and eight sides. | |

circle | A closed plane curve consisting of all points at a given distance from a point within it called the center. | |

trapezoid | A quadrilateral plane figure having two parallel and two nonparallel sides. | |

ray | The part of a straight line considered as originating at a point on the line and as extending in one direction from that point. | |

closed curve | A curve that is continuous and has endpoints that meet at the same point. | |

isosceles triangle | A triangle which has two sides equal. | |

hexagon | A polygon having six sides and six angles. | |

diameter | A straight line passing through the center of a circle or sphere and meeting the circumference or surface at each end. | |

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