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Line

A straight path that goes on forever in opposite directions.

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Line Label

A label that is a line with arrows on both ends.

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Ray

A part of a line that has one endpoint and extends without end in one direction.

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Ray Label

A label that is a line with an arrow on one end

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Angle

A figure formed by two rays or line segments with two endpoints.

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Angle Lable

A label that is similar to a "less than symbol" only flat on the bottom.

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Parallel

The same distance apart at every point.

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Perpendicular

Lines, line segments, or rays are this if they form right angles.

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Oblique Lines

Lines that are not parallel or perpendicular.

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Protractor

A semicircular instrument for measuring and constructing angles.

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Degree

A unit of measuring angles. Also a unit for measuring temperature.

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Right Angle

An angle that measure 90 degrees.

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Intersecting Lines

Lines that cross at the same point.

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Complementary

Two angles whose sum of their measures is 90 degrees.

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Supplementary

Two angles whose sum of their meaures is 180 degrees.

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Acute

Angle greater than 0 degrees and less than 90 degrees.

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Right Angle

A 90 degree angle.

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Obtuse

Angle greater than 90 degrees and less than 180 degrees.

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Straight Angle

A 180 degree angle.

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Reflex Angle

Angle greater than 180 degrees and less than 360 degrees.

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Circle

A shape that measures 360 degrees.

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Counter-Clockwise

Left turn

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Quadrilateral

A two-dimensional figure with four sides.

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Congruent

figures that are the same shape and size.

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Polygon

A closed plane figure with sides made of straight line segments.

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Vertical Angles

A pair of opposite angles formed by intersecting lines.

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Opposite Angles

These angles are formed by two intersecting lines and have the same measure.

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360 degrees

The sum of the interior angles of a quadrilateral.

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180 degrees

The sum of the interior angles of a triangle.

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