Points, Lines, Line Segments, & Rays
Basics on the topic Points, Lines, Line Segments, & Rays
Points, Lines, Line Segments & Rays – Definition
In this learning text we are going to talk about geometry. Geometry is the study of shapes, sizes, angles and dimensions of objects. To understand geometry, we must learn the key definitions, which you will use when learning geometry in different grades. They are: points, lines, line segments & rays.
- A point is a specific location on a flat surface.
- A line is a set of points that extends definitely or without ending in both directions. We often show this by putting an arrow at each end of lines we draw.
- A line segment is part of a line between two endpoints.
- A ray is part of a line that has an end point on one side but extends the other direction without ending.
Let’s look at some real-life examples to see how these concepts work.
Points, Lines, Line Segments & Rays – Examples
Using a baseball field as visual representation, we are going to show points, lines, line segments & rays as real-life examples. For revision, have a look at the table below for an overview of points, lines, line segments and rays.
| Term | Explanation |
|---|---|
| point | A point is a specific location on a flat surface. |
| line | A line is a set of points that extends definitely or without ending in both directions. |
| line segment | A line segment is part of a line between two endpoints. |
| ray | A ray is part of a line that has an end point on one side but extends the other direction without ending. |
Now let’s look at the points on the baseball field: they can represent players on the field. Remember points are created by marking specific locations on a flat surface. Below you can see a baseball diamond with different points. The bases make points, the home plate is a point and the pitching mound is a point too. The points around the field are representing the players. This is just one example to visualize the concept of a point.
Let’s look at examples of lines. A line is created by connecting specific points. The green lines below are never-ending lines because they have the ability to continue forever in both directions. In the picture below we can only see a portion of a line as the line never ends.
In mathematics, we put an arrow at the end of a line which indicates the direction of a never-ending line.
A Line segment is just a small portion or section of a line. We mark the section of a line with endpoints to indicate we are looking at this small part.
On this baseball field, there are many line segments: The joined lines between the bases and home plate are line segments. Each connection from one point to another is a line segment. The line from the pitcher’s plate to the home plate is also a line segment, even the ball thrown from third base to first base will make a line segment.
The line segments can be anywhere, all depending on the position or points where the player is standing.
In a baseball field, a ray can be created when the player is in the batter’s box. The home plate is the position of the end point, and the lines are extended with no endpoints.
As mentioned before, the baseball field is just one of the real-life examples showing points, lines, line segments & rays.
Points, Lines, Line Segments & Rays – Summary
All geometry is based on these concepts:
- A point is a specific location on a flat surface.
- A line is a set of points that extends definitely or without ending in both directions. We often show this by putting an arrow at each end of lines we draw.
- A line segment is part of a line between two endpoints.
- A ray is part of a line that has an end point on one side but extends the other direction without ending.
This text explored the meaning of the terms points, lines, line segments and rays. If you need more information, watch the video and complete the worksheet related to points, lines, line segments & rays.
Frequently Asked Questions about Points, Lines, Line Segments & Rays
Transcript Points, Lines, Line Segments, & Rays
Nico and Nia are trying out for the Geo City Giants. [Coach:] “Today, we hope to have some new members join our team.” [Coach:] “FIRST, We are going to go over some of the fundamentals so LISTEN UP!” Before Nico and Nia can try out for the team, Coach needs to explain, Points, Lines, Line Segments, and Rays. Geometry is the study of shapes, sizes, angles, and dimensions of objects. In order to understand geometry, we need to learn the fundamentals. All geometry is based on these beginning concepts: A POINT is a specific location on a flat surface. A LINE is a set of points that extends indefinitely, or without ending, in BOTH directions. We often show this by putting an arrow at each end of the lines that we draw. A LINE SEGMENT is part of a line between two endpoints. A RAY is part of a line that has an endpoint on one side but extends in the other direction without ending. Using the baseball field as our example, let’s see how these concepts, or ideas, work in everyday life. Points are created by marking specific locations on a flat surface. What points do you see on the baseball diamond? The bases make points, home plate is a point, and the pitcher’s mound is also a point on the field. We can even create more points on the field when we put the players in their positions.
A line is created by connecting a set of points. Look at the foul lines. We say that lines are indefinite, or never-ending because they have the ABILITY to continue forever(...) in both directions. We are only seeing a portion of the line. This end could keep on going, indefinitely, in this direction. When we look at only a section of a line, we call it a LINE SEGMENT. We mark the section of the line with endpoints, to indicate we are only looking at this part. In baseball, there are many line segments. The paths between the points made by the bases are line segments, and from the pitcher’s mound to home plate is a line segment. Even when the third baseman, throws to the first baseman, a line segment is made. Do you see more line segments on the field? Yes, line segments can be anywhere depending on the position, or points, of the players. In baseball, a ray can be created when a player is at-bat. Homeplate is the position of the endpoint… and the lines would extend outward like this. Baseball is one example of how we use geometry in everyday life. While Nico steps up to the plate, let's review. Remember… All geometry is based on these beginning concepts: A POINT is a specific location on a flat surface. A LINE is a set of points that extends indefinitely in BOTH directions. A LINE SEGMENT is part of a line between two endpoints. A RAY is part of a line that has an endpoint on one side but extends in the other direction without ending. "[Coach:] “NICO, you’re up, “Let’s see what ya got!”
