Geometric Jargon

Slide

cube

octagon

Acute AngleAn angle with a measure less than 90

“What a-cute angle!”

AngleTwo rays that share an endpoint

 

  

 

 

 

 

AreaThe measure, in square units, of the

inside region of the 2-dimensional figure

Base of a Solid Figure

A special face of a solid figure

ChordA line segment that joins any two points on a circle

Chord AB

AB

Circle A closed curve with all its points in one

plane and the same distance from the center

Circle

Circumference

The perimeter of a circle

Cone A 3-dimensional figure with 1 curved

surface, 1 flat surface (usually circular), 1 curved edge, and 1 vertex

cone

CompassA tool used to draw circles

Congruent

Having exactly the same size and shape

   

Coordinate GridA two-dimensional system in which the coordinates of a point are its distances

from two intersecting perpendicular lines called axes

Coordina ex

y

Coordinates

An ordered pair of numbers that gives the location of a point on a coordinate grid

CubeA regular solid with 6 congruent square

faces

Square face

Sq

uare

face

Cylinder

A 3-dimensional figure with 2 parallel and congruent circles as bases, 1 curved

surface, 2 curved edges, and 0 vertices

edges

curved surface

base

Diagonal

A line segment that joins two vertices of a polygon but is not a side of the polygon

Diameter A chord that goes through the center of a

circle

Edge The line segment where two faces of a

solid figure meet

Edge

Equilateral TriangleA triangle with all sides the same length

Face A plane figure that serves as one side of a

solid figure

face

Height

The length of a perpendicular line segment from a vertex to the base

height

Hexagon

A polygon with 6 sides

Hexagon

Intersecting Lines

Lines that meet or cross at a common point

in ersec ing lines

Isosceles Triangle

A triangle that has two congruent sides

Congruent Sides

Kite

A quadrilateral with two pairs of adjacent congruent sides

Length

The distance along a line or figure from one point to another

LENGTH

Line

An infinite set of points forming a straight path that goes in two directions without

end

Line Segment

A part of a line defined by two endpoints

 

Line of Symmetry A line that divides a figure into

two congruent halves that are mirror images of each other

Net

A 2-dimensional shape that can be folded into a 3-dimensional figure is a net of

that figure

NEnet of a

cube

Obtuse Angle

An angle with a measure greater than 90º and less than 180º

Parallel Lines (l l)

Lines that never intersect (always the same distance apart)

Parallelogram A quadrilateral with two pairs of parallel

and congruent sides

Pentagon

A polygon with 5 sides

Perimeter

The distance around a figure

Perpendicular linesLines that intersect to form right angles

Plane A flat surface that extends infinitely in all

directions

Polygon

A closed plane figure formed from line segments that meet only at their

endpoints

Prism A 3-dimensional figure that has two congruent and parallel faces that are polygons. The rest of the faces are

parallelograms.

Pyramid

A polyhedron whose base is a polygon and whose other faces are triangles that

share a common vertex

Quadrilateral A polygon with 4 sides

Radius

The segment, or the length of the segment, from the center of the circle

to any point on the circle

Ray

A part of a line that has one endpoint and extends indefinitely in one direction

Rectangle A quadrilateral with two pairs of

congruent, parallel sides and four right angles

Rectangular Prism A prism with 6 rectangular faces

Reflection (flip)A transformation creating a mirror image

of a figure on the opposite side of a line

Rhombus A parallelogram with all 4 sides equal in

length

Right Angle

An angle that measures exactly 90º

Rotation (turn)

A transformation in which a figure is turned a given angle and direction

around a point

Scalene TriangleA triangle that has no congruent sides

Similar FiguresFigures that have the same shape, but not

necessarily the same size

Sphere A 3-dimensional figure made up of all points that are equally distant from a

point called the center

Square

A parallelogram with 4 congruent sides and 4 right angles

Square Pyramid

A pyramid with a square base

Straight Angle

An angle with a measure of 180º

Tessellation

A covering of a plane without overlaps or gaps using combinations of congruent

figures

Three-Dimensional

An object that has length, width, and height

Translation (slide)A transformation that slides a figure a

given distance in a given direction

Trapezoid A quadrilateral with exactly two parallel

lines

Triangle

A polygon with three angles and three sides (“tri” means 3)

Triangular Pyramid

A pyramid with a base that is a triangle

Two-Dimensional

A figure that has length and width, but not height

Vertex

The point at which two line segments, lines, or rays meet to form an angle. Also, a point on a polyhedron where

three or more faces intersect.

VolumeThe number of cubic units it takes to

fill a solid

Volume = 12 cubic units

Width

One dimension of a 2- or 3- dimensional figure

width