A specific location in space with no size or shape. 

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Part of a line containing two endpoints and all the points between them.

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A part of a line that extends indefinitely in one direction from a fixed point. 

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A two-dimensional flat surface that extends in all directions.

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Two rays that are part of the same line and have only their endpoints in common. In the figure, [image] and [image] are opposite rays.

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Three or more points that lie on the same line. In the figure, P, Q, and R are collinear points.[image]

Points or lines that lie in the same plane. In the plane M, points A, B, and C are coplanar, and [image] and [image] are coplanar.

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A figure formed by two rays with a common endpoint. In the figure, [image]RST is formed by [image] and [image] with the common endpoint (or vertex) S.

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On a line segment, the point that is halfway between the endpoints.

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A ray whose endpoint is the vertex of the angle and is located in the interior of the angle. It separates a given angle into two angles with equal measure. In the figure, [image] is the angle bisector of [image]P.

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Having the same measure.

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The common endpoint of the rays forming the angle.

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An angle with a measure greater than 0° and less than 90°.

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An angle that measures more than 90° but less than 180°.

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An angle that measures exactly 90°.

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An angle that measures 180°.

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Two angles are complementary if the sum of their measures is 90°. In the figure, [image]1 and [image]2 are complementary angles.

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Two angles are supplementary if the sum of their measures is 180°.

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Opposite angles formed by the intersection of two lines. In the figure, thevertical angles are [image]1 and [image]3, and [image]2 and [image]4.

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Angles that have the same vertex, share a common side, and do not overlap. In the figure, [image]1 and [image]2 are adjacent angles.

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Lines which meet to form right angles and whose slopes have a product of -1.

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A simple closed figure in a plane formed by three or more line segments.

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A polygon for which a point on at least one of its diagonals lies outside the polygon. In the figure, diagonal [image] lies outside polygon JKLMN. / A polygon for which all diagonals are located in the interior of the polygon.

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A polygon that has all sides congruent and all angles congruent. / A figure that cannot be classified as a single polygon.

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A segment joining two nonconsecutive vertices of a polygon. In the figure, [image] is a diagonal.

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The segments that form a closed figure. 

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The distance around a closed geometric figure.

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