# Point

A point is an exact position or location on a plane surface.

# Line

A line has only one dimension. It continues forever in two directions.

# Plane

Flat two-dimensional object.

# Intersecting Lines

Two or more points that meet at a point are called intersecting lines.

# Parallel Lines

Two lines in the same plane that never intersect.

# Vertical Line

A line parallel to the sides of a page or sheet as distinguished from a horizontal line.

# Horizontal Line

Parallel to or in the plane of the horizon or a base line.

# Parallel Planes

Parallel Planes are planes in the same three-dimensional space that never meet.

# Acute Angle

An angle that measures less than ninety degrees but more than zero degrees.

# Obtuse Angle

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

# Right Angle

An angle of 90 degrees as in a corner of a square or at the intersection of two perpendicular straight lines.

# Square

A four sided flat shape with straight sides where all sides have an equal length.

# Rectangle

A rectangle is a four sided flat shape where every angle is 90 degrees.

# Circle

A round plane figure whose boundary consists of points equidistant from a fixed point.

Half a circle.

# Cube

A symmetrical three dimensional shape, either solid or hollow,contained by six equal squares.

# Octagon

A plane figure with eight straight sides and eight angles.

# Cylinder

A solid geometric figure with straight parallel sides and a circular or oval section.

# Congruent Circles

Two circles with the same diameter.

# Chord of a Circle

Geometric line segment whose endpoints both lie on the circle.

# Central Angle of a Circle

Angles formed by any two radii in a circle. The vertex is the center of the circle.

# Cone

A solid or hollow object that tapers from a circular or roughly circular base to a point.