What Is a Line?
A line is a one-dimensional figure without any width, and can be extended indefinitely to the left and right. The points lying on a line are called collinear points.
Let’s consider an example:
This line is named as:
or
The double arrow shows that the line can extend on both sides indefinitely.
What Are the Properties of a Line?
The properties of a line are:
- A line is a collection of points in a straight direction
- A line does not have endpoints
- Both sides of the line can be extended to infinity
- It is a one-dimensional figure, that is, it has length but no width or height
What Are the Types of Lines?
There are 6 types of lines:
- Intersecting lines
- Parallel lines
- Coincident lines
- Horizontal lines
- Vertical lines
- Perpendicular lines
Let’s study about each of these types in more detail.
- Intersecting lines
Intersecting lines are two or more lines that have a common point, indicating that they intersect at that point. In other words, intersecting lines are defined as two or more lines crossing each other.
- Parallel lines
Parallel lines are straight lines that never intersect or cross each other, and are at a constant distance from each other.
- Perpendicular lines
Perpendicular lines are intersecting lines forming a right angle at the point of intersection.
- Coincident lines
Coincident lines are the lines that lie upon each other in such a way that when we look at them, they appear to be a single line,
instead of two or more independent lines.
- Horizontal line
Horizontal lines run horizontally, that is, they go from right to left, or in the opposite direction, from left to right.
- Vertical line
Vertical lines move from up to down or from down to up.
Solved Examples
Example 1: Identify the type of lines in the image.
Solution:
Both lines are crossing each other.
So, the lines in the image are intersecting lines.
Example 2: Which of the lines in the image are perpendicular?
Solution:
Lines KO and LM appear to be intersecting at right angles at point M.
So, the lines KO and LM are perpendicular lines.
Example 3: Jacob says that line ‘a’ is parallel to line ‘b’ because they are not intersecting. Has Jacob made the right observation?
Solution:
The lines ‘a’ and ‘b’ are not intersecting but they do not appear to be at the same distance from each other. At the top of the image, the distance between them is shorter than the distance between the two lines at the bottom of the image.
So, the line ‘a’ is not parallel to line ‘b’. Therefore, Jacob’s observation is not right.
A line segment is a part of a line and it has two endpoints.
Parallel lines are straight lines that never intersect or cross each other. There’s always a constant distance between parallel lines. So, parallel lines do not have any common point of intersection.
A ray is a part of a line that runs indefinitely in one direction and has an endpoint at one end.
Point refers to an accurate position in space. It is represented by a dot and does not have any dimensions.