Vocabulary (Geometry)

Created by msmmwelch 

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40 terms · Shapes and Solids

point

An exact location in space.

line

An endless straight path. Has no end points

ray

Part of line that goes on forever in one direction. Has one end point.

segment

Part of a line between two end points.

plane

An endless flat surface. Defined by three points.

angle

Formed by two rays with the same endpoint (vertex).

right angle

An angle that measures 90 degrees.

acute angle

An angle that measures less than 90 degrees.

obtuse angle

An angle that measures more than 90 degress.

straight angle

An angle that measures 180 degrees.

parallel lines

Lines, in the same plane, that never intersect.

Intersecting lines

Lines that intersect at any point.

perpendicular lines

Lines that intersect at right angles.

polygon

A closed, plane (flat) figure, formed by three or more line segments.

regular polygon

A polygon that has sides of equal measure, and has angles of equal measure.

triangle

3 sides, 3 angles

quadrilateral

4 sides, 4 angles

pentagon

5 sides, 5 angles

hexagon

6 sides, 6 angles

octagon

8 sides, 8 angles

congruent

figures that have the same size and shape.

similar

figures that have the same shape, but different sizes.

line of symmetry

A line that divides a figure into two congruent parts.

180

Degrees in a triangle.

360

Degrees in a quadrilateral.

polyhedron

A solid figure with faces that are polygons.

prism

A polyhedron that has two congruent (exactly the same) bases.

pyramid

A polyhedron with only one base.

edge

Line where two faces come together.

faces

The flat surfaces of solid figures

vertex (vertices)

The point where several edges come together.

transformation

Movement of a figure that does not change it's size or shape.

translation

Sliding of a figure in a straight line. The figure does not change direction.

reflection

Flipping a figure over a line (mirror). Figure is now in the opposite direction.

rotation

Turning a figure around a point (vertex). Placing your finger on one corner of the figure, and turing the object around your finger.

heptagon

7 sides, 7 angles.

nanagon

9 sides, 9 angles.

decagon

10 sides, 10 angles.

90

Degrees in a right angle.

square

An equilateral parallelogram with one right angle.

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