Perpendicular Lines Definition

Perpendicular lines is a particular term used in Geometry, Mathematics. These lines are defined as any two lines that intersect each other by making an angle of 90 degrees. It means that these lines are drawn at the right perpendicular to each other.


Read about Altitude in Geometry here in detail.

Representation of Perpendicular Lines

In Mathematics, two perpendicular lines are represented by inserting a particular symbol between the names of those lines. For example, you can represent two perpendicular lines AB & CD as AB ⟂ CD. The symbol between their names shows that these lines are perpendicular to each other.

Real-life examples of Perpendicular Lines

To understand this concept, you can have a look at your surroundings and imagine multiple perpendicular lines in different objects and places. Here we are going to show you a few examples from real life regarding Perpendicular Lines.

For better understanding, let us show you a few perpendicular lines and real-life examples in picture format.

  • The height and width of the TV make a set of perpendicular lines.
  • The hands of a clock at 3’O clock and 9’O Clock makes the angle 90 degrees.

Opposite of Perpendicular Lines

Like these lines, there are other sets of lines two with opposite properties to these lines. Such lines are called opposite to perpendicular lines. In Geometry, those lines are called Parallel lines because they are making an angle of 0 degrees.

In simple words, you can say that these lines drawn side by side without touching each other.


Read about Parallel lines here in detail.

Fun Facts about Perpendicular Lines

  • Two parallel lines can intersect each other at a single point only.
  • Multiple perpendicular lines can be drawn on a single line.
  • Two lines with the same perpendicular line will always be parallel to each other.
  • Only two lines can be perpendicular to each other at a time.

How to construct Perpendicular lines?

It is pretty simple to draw perpendicular lines in Mathematics. You can do this by using simple geometrical equipment or tools. Here are those tools with the discussion of processes through which you can draw these lines.

Using Protractor

  • Draw a horizontal line on the page of your copy.
  • Keep Protractor on that line in such a way that the line of the Protractor lies just above your drawn line
  • Mark a point where the 90 degrees of the Protractor is pointing above your line.
  • Take a ruler and draw a straight line joining that dot with your line.
  • Now, the line you have just drawn will be perpendicular to the first line and vice versa.

Using Compass

You can also draw perpendicular lines with the help of a Compass. It is a little bit more difficult process than the above-mentioned one. Here are the steps that you have to follow one

  • Draw a line on the page of your copy.
  • Mark a point, let's say A, where you want to draw a perpendicular.
  • Take a compass and open it with your desired radius.
  • Draw an arc on both sides of point “A” with the same radius on the line.
  • Label those points for understanding, let's say those points as “X” and “Y”.
  • Open the compass a bit more and draw two arcs above the line by keeping it at “X” and “Y” points.
  • Mark the point of intersection of those arcs as “B” for understanding.
  • Now, draw a line joining “A” and “B” using a ruler.
  • The line AB is perpendicular to the first line that you have drawn in the beginning.


What is the difference between parallel and perpendicular lines?

There are multiple differences between these lines. But you can say that two lines making an angle of 90 degrees are perpendicular while two lines making an angle of 0 degrees are parallel lines.

Can perpendicular lines intersect?

Yes, perpendicular lines must intersect each other.

Are all intersecting lines perpendicular?

No, all intersecting lines are not perpendicular. The lines that are making an angle of 90 degrees are termed perpendicular lines.

Can two lines be perpendicular and parallel at the same time?

No, two lines can either be perpendicular or parallel at the same time.

How many lines be perpendicular to a single line?

Multiple perpendicular lines can be drawn on a single line. Keep in mind that the angle between the drawn lines with the original line should be exactly 90 degrees.