Points, lines, line segments, and rays

In this lesson, we will learn:

• Points, Lines, Line Segments and Rays are basic figures in math that can be used to construct more complicated figures (i.e. angles, shapes, parallel/perpendicular lines, etc.)

• A point is a dot with position but no size nor shape (undefined) $\,$
• There are an infinite number of points in figures (i.e. you can draw many points between endpoints in a line segment) $\,$
• The proper notation of a point is just to write the named letter (ex. point $A$)

• A line has no beginning/end; an ongoing straight path of points
• The arrows on both sides mean that it can extend infinitely in that direction
• The proper notation of a line is to write the letters of two points in the figure and draw a double-sided arrow above the letters (ex. line $\overleftrightarrow{AB}$)


• A line segment is a part of a line with two finite endpoints
• A line has arrows on both ends whereas the line segment has endpoints on both ends; the line continues forever, where the line segment ends where it is drawn
• The proper notation of a line segment is to write the letters of the two endpoints and draw a bar above the letters (ex. line segment $\overline{AB}$)


• A ray starts at one endpoint and extends in one direction
• One end of the ray has a point, whereas the other end of the ray has an arrow
• The proper notation of a ray is to write the letters of two points in the figure (starting with the letter of the endpoint) and draw a one-sided arrow above the letters (ex. ray $\overrightarrow{AB}$ )