Basics of Geometry #1: Points, Lines, Rays, Line Segments, and Angles

Points

A point is a specific location in space. It is usually named with a single letter and represented by a dot. For example, Point B might look like this:

Lines

A line extends infinitely in two opposite directions, forming a straight path that connects two points and continues beyond them.

A line is usually named with two letters representing two points on it, with an arrow over the letters pointing in both directions to indicate that the line extends forever. A drawing of a line should be straight with arrows at both ends.

For example, Line AB (also called Line BA) might look like this:

Line Example

Another way to represent a line is with a lowercase letter. For example, line p might look like this:

Another Example of a Line

Rays

A ray is a part of a line that has one endpoint and extends infinitely in one direction, away from the endpoint.