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point

an exact location in space

line

an infinite set of points forming a straight path extending in opposite directions

line segment

a part of a line that consists of the two endpoints and all the points of the line between them

ray

a part of a line that has one endpoint and extends infinitely in one direction

midpoint

the point on a line segment that divides it into two equal segments

angle

the union of two rays that share a common endpoint

plane

a flat surface with infinite lengthe and width but no thickness

collinear

on the same line

perpindicular lines

lines that intersect to form a right angle

parallel lines

lines in the same plane that do not intersect

supplementary angles

two angles with measures whose sum is 180 degrees

interior angle

An angle on the inside of a polygon, formed by the sides of the polygon (see GSP3

Exterior angle

: An angle formed by the side of a polygon and an extension of an adjacent side. At each vertex, there are two exterior angles (see GSP3

Adjacent angles

Angles that share a common ray and endpoint, but that do not overlap

Linear pair

A linear pair of angles is formed when two lines intersect. The angles are adjacent and formed by the two intersecting lines. Below, and are a linear pair

vertex

The common endpoint of two rays or segments (plural: vertices)

Polygon

A closed figure formed by line segments that meet only at their endpoints

Regular polygon

A polygon that has all sides congruent and all angles congruent.

Triangle

A three-sided polygon

Quadrilateral

A four-sided polygon

Pentagon

A five-sided polygon

Hexagon

A six-sided polygon

Septagon

A seven-sided polygon

Octagon

An eight-sided polygon

Nonagon

A nine-sided polygon

Decagon

A ten-sided polygon

Interior angle

An angle on the inside of a polygon, formed by the sides of the polygon (see GSP 3

Exterior angle

An angle formed by the side of a polygon and an extension of an adjacent side. (see GSP

Linear pairs are supplementary

Linear pairs are supplementary

The sum of the interior angles of a convex polygon with n sides is 180(n - 2)0

The sum of the interior angles of a convex polygon with n sides is 180(n - 2)0

The sum of the exterior angles of all convex polygons is 3600

The sum of the exterior angles of all convex polygons is 3600