Geometry - Basic Vocab

Front

Point

Back

A location in space that has no size—no length, width, or depth. It's usually represented by a dot and labeled with a capital letter.

Front

Line

Back

A straight path that goes on forever in both directions. It has no thickness and is made up of an infinite number of points.

Front

Line Segment

Back

A part of a line with two endpoints. It has a definite beginning and end.

Front

Ray

Back

A part of a line that starts at one point and goes on forever in one direction.

Front

Angle

Back

Formed by two rays (or segments) with a common endpoint. It measures the amount of turn between the two sides.

Front

Vertex

Back

The point where two sides, rays, or line segments meet to form an angle.

Front

Plane

Back

A flat surface that extends forever in all directions. Think of it like an endless sheet of paper.

Front

Congruent

Back

Figures that are the same size and shape. Their corresponding sides and angles are equal.

Front

Similar

Back

Figures that have the same shape but not necessarily the same size. Corresponding angles are equal, and corresponding sides are proportional.

Front

Complementary Angles

Back

Two angles whose measures add up to 90°.