Geometry Vocabulary

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Rectangular Prism


Triangular Prism


Rectangular Pyramid


Square Pyramid


Sphere


Cylinder


Cone
A flat shape Plane Figure
Three dimensions, length, width, and height Solid Figure
A flat surface on a solid figure Face
3 or more edges meet Vertex
Line segment where 2 faces meet Edge
Pattern that can be used to make a solid Net
A closed plane figure made up of line segments Polygon
3 Sides

Triangle
4 Sides

Quadrilateral
5 Sides

Pentagon
6 Sides

8 Sides

Octogon
An exact location in space Point
A straight path of points that goes on and on in 2 directions Line
Part of a line. Has two endpoints Line segment
Part of a line. Has 1 endpoint and continues on in 1 direction Ray
Formed by 2 rays that have the same endpoint Angle
Common endpoint in an angle Vertex

A square corner
(90 degrees)


Right Angle

Less than a right angle (< 90 degrees)

Acute Angle
Greater than a right angle (> 90 degrees)

Obtuse Angle

Forms a straight line
(180 degrees)


Straight Angle
Lines that never intersect

Parallel Lines

Lines that pass through the same point

Intersecting Lines

Lines that form right angles

Perpendicular Lines

Triangle with all sides the same length

Equilateral Triangle

Triangle where at least 2 sides are the same length

Isosceles Triangle

No sides of the triangle are the same length

Scalene Triangle

One angle of the triangle is 90 degrees

Right Triangle
All 3 angles of the triangle is < 90 degrees

Acute triangle

One angle of the triangle is > 90 degrees

Obtuse Triangle

4 right angles

Rectangle

4 right angles and all sides are the same length

Square
There is only one pair of parallel sides

Trapezoid
Opposite sides are parallel

Parallelogram
Opposite sides are parallel and all sides are the same length

Rhombus
Closed plane figure with all points the same distance from the point

Circle
Point in the middle of the circle

Center
Any line segment that connects 2 points on the circle and passes through the center

Diameter
Any line segment that connects the center to a point on the circle

Radius
Any line segment that connects 2 points on a circle

Chord
Moves a figure in a straight direction

Slide or translation
Mirror image of a figure

Flip or reflection
To move a figure about a point

Turn or rotation
Figures that have the same size and shape

Congruent
Tile patters that can be drawn by sliding, flipping, or turning shapes

Tessellations
A figure that can be folded into 2 congruent halves that fit on top of eachother

Symmetric
When folding a symmetric figure you create a ___ __ ______

Line of Symmetry
Figures that have the same shape but may or may not have the same size

Similar Figures
The distance around a figure

Perimeter (L+L+W+W)
The number or square units to cover the region inside a figure

Area (L x W)
Sum of the area of all of its faces on a prism

Surface Area
Number of cubic units needed to fill a solid figure

Volume (L x W x H)