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# geometry definitons

### Geometry definitons

Question | Answer |
---|---|

acute triangle | A triangle in which all three angles are acute |

angle | A figure formed by two rays that have a common endpoint |

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

circle | A closed plane figure with all points on the figure the same distance from the center |

circumference | The distance around a circle |

closed figure | A figure that begins and ends at the same point |

cone | A solid figure that has a circular base and one vertex |

congruent | Having the same size and shape |

congruent figures | Figures that have the same size and shape |

coordinate plane | A plane formed by two intersecting and perpendicular number lines called axes |

coordinates | The numbers in an ordered pair |

cube | A solid figure with six congruent square faces |

cylinder | A solid figure that has two parallel bases that are congruent circles |

degree (°) | A unit for measuring angles and temperature |

diameter | A line segment that passes through the center of a circle and has its endpoints on the circle |

dimension | A measure in one direction; the length, width, or height of a figure |

edge | The line segment where two faces of a solid figure meet |

equilateral triangle | A triangle with three congruent sides |

face | A polygon that is a flat surface of a solid figure |

figurate numbers | Numbers that can be represented by geometric figures |

hexagon | A polygon with six sides and six angles |

hypotenuse | In a right triangle, the side opposite the right angle; the longest side in a right triangle |

intersecting lines | Lines that cross at exactly one point |

isosceles triangle | A triangle with two congruent sides |

line | A straight path in a plane that goes on forever in opposite directions |

line segment | A part of a line that includes two points, called endpoints, and all of the points between them |

line symmetry | A figure has line symmetry if a line can separate the figure into two congruent parts |

obtuse angle | An angle whose measure is greater than 90° and less than 180° |

obtuse triangle | A triangle that has one obtuse angle |

octagon | A polygon with eight sides |

ordered pair | A pair of numbers used to locate a point on a coordinate plane; the first number tells how far to move horizontally and the second number tells how far to move vertically |

parallel lines | Lines in a plane that never intersect |

parallelogram | A quadrilateral whose opposite sides are parallel and congruent |

pentagon | A polygon with five sides |

perpendicular lines | Two lines that intersect to form four right angles |

pi | The ratio of the circumference of a circle to its diameter |

plane | A flat surface that extends without end in all directions |

plane figure | A figure which lies in a plane |

point | An exact location in space, usually represented by a dot |

point symmetry | When a figure can be turned half way about a central point and still look the same |

polygon | A closed plane figure formed by three or more line segments |

polyhedron | A solid figure with flat faces that are polygons |

prism | A solid figure that has two congruent, polygon-shaped bases, and other faces that are all rectangles |

protractor | A tool used for measuring or drawing angles |

pyramid | A solid figure with a polygon base and all other faces triangles that meet at a common vertex |

quadrilateral | A polygon with four sides |

radius | A line segment with one endpoint at the center of a circle and the other endpoint on the circle |

ray | A part of a line, with one endpoint, that continues without end in one direction |

rectangle | A parallelogram with four right angles |

rectangular prism | A solid figure in which all six faces are rectangles |

reflection (flip) | A movement of a figure to a new position by flipping it over a line |

regular polygon | A polygon in which all sides are congruent and all angles are congruent |

rhombus | A parallelogram with four congruent sides |

right angle | An angle formed by perpendicular lines, line segments, or rays and with a measure of 90° |

right triangle | A triangle with one right angle |

rotation (turn) | A movement of a figure by turning it around a fixed point |

rotational symmetry | The property of a figure that can be rotated less than 360° around a central point and still be congruent to the original figure |

scale drawing | A drawing that shows a real object smaller than (a reduction) or larger than (an enlargement) the real object |

scalene triangle | A triangle with no congruent sides |

similar figures | Figures with the same shape but not necessarily the same size |

solid figure | A three-dimensional figure |

sphere | A solid figure that has the shape of a round ball; all points are the same distance from the center |

square | A rectangle with 4 equal sides |

Created by:
brandonnichols