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Difference Between Line and Line Segment

Last updated date: 22nd Jul 2024
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What is a Line Segment and a Line?

In geometry, you often come across terms such as a point, line, rays, segments, angles etc. The line is the most often in-use term that’s you find in your geometry text-book. Today we take a look at what is a line segment. We also take a look at the difference between a line and line segment. In simple words, a line is a distance that joins any two given points. A line is always straight and extends infinitely in both the directions. In contrast, a line segment has marked boundaries, i.e. it has a fixed starting point and a fixed ending point. 


Definition of a Line 

A line is the shortest distance between any two given points in a plane. A line is always straight. Curved, sloping or uneven figures that do not run a straight distance is not a line. The best way to define a line is to say that a lien is a connection between two points.


What is a Line Segment? 

A line segment is a part of a line with definite endpoints on both sides (starting and ending points). Lines run in the infinite distance in both the directions whereas a line segment is a part of a line. A line segment is a distance that joins two points on a line. It is that part of a line that connects two ends of the same path. A line segment has endpoints.

There are essential differences between line and a line segment. It is essential to understand the features that set a line apart from the line segment. Let us study some of the significant differences between the two terms.

Difference Between Line and Line Segment                                          


Line Segment 

A line has no definite endpoints.

A line segment has definite endpoints.

A line can extend in both the directions.

A line segment can extend but not in either direction.

The length of a line is indefinite.

The length of a line segment is definite.

A line has no start or endpoint.

A line segment has both -start and endpoint.

A line is continuous, infinite and straight.

A line segment is a small part of a line. 

The length of a line cannot be measured.

Length of a line segment can be measured.

Different Types of Lines 

You know that that a line is infinite, it has no ends, and it is always straight. However, it is essential to understand that the line has different forms too. Let us know about the different types of lines in geometry. The four types of lines that you have often heard about are:

  1. Horizontal Line – it runs straight from left to right.

  2. Vertical Lines – it runs straight from top to bottom

  3. Perpendicular lines – when two straight lines intersect each other at a right angle, two lines are said to be perpendicular to each other.

  4. Parallel lines – when two lines never cross or meet each other no matter how many extensions they may get, these two lines are parallel to each other.

About Line Segments 

When you write seg PQ, it means that a part of the more significant line links the point P and Q on the line. P and Q are the endpoints of the segment. The word segment itself denotes a piece of something. Here, in geometry, it is a portion or small part of the bigger line. A line will extend to infinity in both the directions and cannot be measured, but a segment can be estimated.

About the Naming of Line Segments 

Line segments get names in two common ways:

  1. Naming of a Line Segment By the Endpoints

In this method, the line segment is PQ as it links the two points, P and Q. It is essential to remember that points usually get a denotation in the capital letters. So, you have to write a line segment as line segment PQ. There is a bar or a small line over the two letters that is an indication that the two letters, PQ is a line segment.

  1. Naming a Line Segment By a Single Letter 

In this type of naming, the segment gets a marking by a single small letter such as p, q or x. in this type, small letters are in use for naming the sides of triangles and polygons.

Fun Facts 

A line segment is a composition of two words- a line and a segment. The line has its origins in the Latin, old English, and Old French language- it means a rope or series. The word segment comes from Latin segmentum a strip or cut-off piece.

FAQs on Difference Between Line and Line Segment

1. Can a line have curves? 

A line cannot have curves. It cannot even have corners. If you see a line that has an edge, it means that there are multiple lines. A single line cannot have corners and curves. If in a line AB, A joins B then isn’t a line. You can have only one line passing between A and B. Even corner angles of a triangle or other geometric shape cannot be called a line. In order to be termed as a line, it has to have neither the starting point nor the ending point. On paper, it is often represented by arrowheads on both sides (to depict never-ending endpoints)

2. What are examples of line segments?

The most common examples of a line segment include the sides of a triangle or square. The chord joining two points on a circle is also a segment. When you see an actual chessboard that has the shape of a quadrilateral, it has four-line sections. You can see many examples of line segments in real life; however, this is not the case with a line segment. You can have one and only one line segment between two given points on a line.