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20 Cards in this Set
 Front
 Back
Congruency

Geometric figures having the same size and shape; all corresponding parts of congruent figures have the same measure.


Perpendicular

Lines in the same plane which intersect to form a right angle.


Parallel

Lines that lie in the same plane and never meet. Also, planes lying in space that never meet.


Similarity

Two or more figures having the same shape but not necessarily the same size.


Symmetry

A figure has symmetry if there exists some line or point through which all points of the figure can be reflected to generate another point on the figure.


Threedimensional

An object that has length, width, and height.


Twodimensional

A figure that has length and width but not height (i.e., a plane figure such as a rectangle or circle)


Vertex (vertices)

The points where two line segments come together (corners).


vertical angles

When two lines intersect, they make four angles at the vertex. The angles opposite each other are equal in size and are called vertically opposite angles.


complementary angles

Two angles for which the sum of their measures is 90°.


straight angle

An angle which measures 180°.


supplementary angles

Two angles for which the sum of their measures is 180°.


straightedge

An object that can be used to draw straight lines.


adjacent angles

Two angles positioned in the same plane that have a common side and a common vertex.


acute angle

A sharply pointed angle with size less than a right angle (<90°).


protractor

An instrument used to measure and draw angles.


obtuse angle

An angle that measures more than a right angle (greater than 90°) but smaller than a straight angle (180°).


compass

An instrument used to draw a circle and to mark off equal lengths.


angle

The space between two straight lines with a common endpoint or vertex.


right angle

An angle measuring exactly 90°.
