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# 6th Math 3rd 9 wks.

### vocabulary for RISD's 3rd 9 weeks

vocabulary word | definition |
---|---|

line | a straight path that extends infinitely in opposite directions |

line segment | a part of a line with 2 endpoints |

midpoint | the point on a line segment that divides it into 2 congruent parts |

ray | a part of a line that has one endpoint and extends forever in the opposite direction |

intersecting lines | two lines that cross at exactly one point |

perpendicular lines | lines that intersect at one point and form right angles |

parallel lines | two lines in the same plane that never intersect |

skew lines | lines that lie in different planes and are neither parallel nor intersecting |

right angle | an angle with a measure of 90 degrees |

obtuse angle | an angle with a measure of more than 90 degrees but less than 180 degrees |

acute angle | an angle that measures greater than 0 degrees and less than 90 degrees |

adjacent angles | angles that share a common ray, have a common vertex and do not overlap |

vertical angles | a pair of opposite congruent angles formed by intersecting lines |

vertex/vertices | the point where 2 rays meet, where 2 sides of a polygon meet, or where the edges of a 3-dimensional shape meet; the top point of a cone or pyramid |

straight angle | an angle whose measure is 180 degrees |

right triangle | a triangle with one right angle |

obtuse triangle | a triangle with one obtuse angle |

acute triangle | a triangle with 3 acute angles |

scalene triangle | a triangle with no congruent sides |

equilateral triangle | a triangle with 3 equal sides |

isosceles triangle | a triangle with two congruent sides |

congruent | having the same shape and the same size |

symmetry | a figure has line symmetry if a line can divide the figure into 2 congruent parts |

transformation | a change in size, shape, or position of a geometric figure |

reflection | a transformation that produces a mirror image of a geometric figure (flip) |

translation | a transformation that moves a geometric figure by sliding each of the points the same distance in the same direction (slide) |

rotation | a transformation of a figure by turning it about a fixed point (turn) |

quadrilateral | a four sided polygon |

pentagon | a five sided polygon |

hexagon | a six sided polygon |

octagon | an eight sided polygon |

decagon | a ten sided polygon |

rhombus | a parallelogram whose 4 sides are congruent and whose opposite angles are congruent |

parallelogram | a quadrilateral with opposite sides parallel and congruent |

trapezoid | a quadrilateral that only has one pair of parallel sides |

polygon | a closed figure made of line segments |

regular polygon | a polygon in which all sides are the same length and all angles have the same measure |

prism | a 3 dimensional shape with 2 parallel, congruent bases; all other faces are parallelograms |

cylinder | a 3 dimensional figure with 2 parallel bases that are congruent circles |

sphere | a 3 dimensional shape with all points an equal distance from the center |

cone | a 3 dimensional shape with a circular base, a curved surface, and one vertex |

face | a flat surface of a 3 dimensional shape |

edge | the line segment where 2 faces of a 3 dimensional shape meet |

customary system of measurement | the measurement system used most often in the United States |

Metric System of Measurement | a measurement system used throughout the world based on multiples of 10 |

gram | a standard unit for measuring mass (weight) in the metric system |

liter | a metric system of measurement for capacity |

meter | a metric system unit for measuring distance |

capacity | a measure of liquid a container will hold |

degree | a unit of measure for angles and for temperature |

area | the number of square units needed to cover a surface (all of the inside of a shape) |

perimeter | the distance around a 2 dimensional shape |

Pi | the ratio of the circumference of a circle to its diameter |

circumference | the distance around a circle |

radius | a line segment from the center of a circle to any point on the circle |

central angle | an angle that has its vertex at the center of a circle |

chord | a line segment whose endpoints are on the circle |

volume | the number of cubic units needed to fill the space occupied by a solid |

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

cubic units | what volume is measured in |

Created by:
ltimmermann