click below

click below

Normal Size Small Size show me how

# Unit 5 Geometry

### Geometry Vocabulary

Term | Definition |
---|---|

Base | a face of a three-dimensional shape (solid), usually the face on which it stands |

edge | the line segment along which two faces of a three-dimensional shape (solid) meet |

vertex or corner | the point at which the sides of a two-dimensional (flat) shape or the edges of a three-dimensional shape (solid) intersect |

triangular prism | a three-dimensional shape (solid) with 2 triangular bases and 3 rectangular faces |

face | a flat surface of a three-dimensional shape (solid) |

cube | a three-dimensional shape (solid) whose 6 faces are all squares |

prism | a three-dimensional shape with 2 congruent bases that each have 3 or more sides |

rectangular prism | a three-dimensional shape (solid) whose 6 faces are all rectangles |

scale | to increase or decrease in size by a particular ratio |

symmetry | the property of a shape that can be folded so that the two halves match exactly |

line of symmetry | a real or imaginary line that divides a shape into two mirror images |

reflection | a flip of a geometric figure |

rotation | a turn of a geometric figure |

translation | a slide of a geometric figure |

congruent | of the same shape and size; two shapes are congruent if one can be exactly superimposed onto the other using a sequence of rotations, reflections, and/or translations |

degree | a unit used to measure the size of angles; 1 degree is equal to 1⁄36 of a full rotation |

angle | the figure formed by 2 rays or line segments that share an endpoint; often measured in terms of the amount of rotation (expressed as some number of degrees) needed to superimpose one of those rays or line segments onto the other |

right angle | an angle with a measure of exactly 90° |

straight angle | an angle with a measure of exactly 180° |

obtuse angle | an angle with a measure greater than 90° and less than 180° |

acute angle | an angle with a measure greater than 0° and less than 90° |

zero angle | an angle whose measure is zero degrees |

protractor | a tool used to measure angles (including angles you want to draw) |

hemisphere | half of a sphere |

circle | a two-dimensional (flat) shape made by drawing a curve that is always the same distance from a point called the center |

circumference | the distance around a circle, cylinder, or widest part of a sphere |

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

diameter | a line segment between two points on a circle that passes through the center of the circle |

line | a set of connected points that continues in both directions without end (if it has two endpoints it is a line segment, and if it has one endpoint and continues in one direction without end, it is a ray) |

parallel | always the same distance apart |

intersecting lines | lines that contain one common point |

perpendicular | intersecting at right angles |

line segment | the set of all points between two endpoints |

ray | a set of connected points that continues in one direction without end |

triangle | a two-dimensional (flat) shape with 3 sides |

isosceles triangle | a triangle with exactly 2 congruent sides |

scalene triangle | a triangle whose sides are all of different lengths |

equilateral triangle | a triangle with all sides the same length |

right angle | an angle with a measure of exactly 90° |

hexagon | a two-dimensional (flat) shape with 6 sides |

rectangle | a two-dimensional (flat) shape with two pairs of parallel sides (4 sides total) and 4 right angles |

rhombus | a two-dimensional (flat) shape with 4 congruent sides |

quadrilateral | a two-dimensional (flat) shape with 4 sides |

square | a two-dimensional (flat) shape with 4 congruent sides and 4 right angles |

parallelogram | a two-dimensional (flat) shape with 4 sides, with both pairs of opposite sides parallel |

trapezoid | a two-dimensional (flat) shape with 4 sides, exactly 1 pair of which are parallel |

polygon | a closed two-dimensional (flat) shape with 3 or more sides |

pentagon | a two-dimensional (flat) shape with 5 sides |

square unit | a square with sides that measure 1 unit, used to measure area |

cubic unit | a unit used to measure volume (e.g., cubic centimeter, cubic inch) |

tile | to cover in square units to measure or illustrate area |

perimeter | the distance in linear units around a two-dimensional (flat) figure; the perimeter of a circle is called the circumference P= (2 x width) + (2 x length) |

volume | the total number of cubic units needed to fill a three-dimensional space |

area | the total number of square units needed to cover a two-dimensional surface A= length x width |