Types of lines – Classification – Diagram

Types of lines

Lines are classified into three types based on the nature of their endpoints.

• Straight line 

• Line segment

• Ray

A group of lines are further classified into two types based on the nature of the intersection between these lines.

• Intersecting lines

• Parallel lines 

Two intersecting lines can be perpendicular lines when the angle between them is equal to 90 degrees.

Based on the inclination, lines are classified into two types: 

• Horizontal line

• Vertical line

We will now read about these lines mentioned above in detail.

Straight Line

• A straight line is a combination of many points along a straight path having no end in both directions. 
• Its length is indefinite.
• It has zero width and hence is a one-dimensional figure.
• In the figure shown below, the arrow on both sides indicates that the straight line extends indefinitely in both directions.

Line segment 

• A line segment is a part of the straight line having two fixed ends.
• Its length is definite.
• It has zero width.
• In the figure shown below, AB is a line segment having two endpoints A and B.

Ray 

• A ray is a part of the straight line having only one endpoint and extending infinitely in the other direction.
• Its length is not definite.
• It has zero width.
• In the figure given below, the arrow on one side indicates that the ray extends indefinitely in one direction.

Intersecting lines

• When there exists a point that lies on both the lines, then these lines are termed as intersecting.
• In the figure given below, point P lies on both lines. In other words at this point, both lines meet each other. P is also known as the point of intersection in this case.

Parallel Lines

• The lines that can never meet each other even are known as parallel lines.
• In other words, there is no common point present on both lines.
• The distance between two parallel lines is constant throughout the lines.
• In the figure given below, lines AB and PQ are parallel to each other.

Perpendicular lines

• When two lines intersect each other such that the angle between them is equal to 90°, then these are known as perpendicular lines.
• In the figure given below, the angle between line AB and PQ is 90°.

Horizontal Line

The line parallel to the x-axis is termed the horizontal line. They span from left to right. Horizontal lines are perpendicular to vertical lines.

In the figure given above AB is a horizontal line.

Vertical Line

The line parallel to the y axis is termed the vertical line. They span from bottom to top. Vertical lines are perpendicular to horizontal lines.

In the figure given above PQ is a vertical line.