# Definition of perpendicular lines explained

Learn and know what is the definition of perpendicular lines in geometry chapter. Perpendicular lines comes under one of the types of lines.

The different types of lines are concurrent lines, intersecting lines, parallel lines and perpendicular lines. All these lines definitions is important to know for the students. Through diagrammatic representation also we can learn what these lines are; in fact it is the best way to learn the different lines. In this method everyone will understand it very easily. Now we will know what are called as perpendicular lines and perpendicular lines definition.

## What is a line in geometry?

As we are discussing about perpendicular lines, before that we should discuss and know what is a line? In a simple way the line is explained as “A group or combination of points joined in a particular order is called as a line”.

### Perpendicular lines definition as follows

We say the definition of perpendicular lines as “Any two lines we call it as perpendicular lines if they make ${ 90 }^{ 0 }$ angle when they intersect. If we want to say exactly “Suppose if we observe the angle between 2 given lines is ${ 90 }^{ 0 }$, then that 2 lines are called as perpendicular lines”. In this way we can give definition of perpendicular lines.

#### How to check whether the given lines are perpendicular or not?

From perpendicular lines definition, it is clear that the angle among two lines should be ${ 90 }^{ 0 }$. But each and every time we cannot check. So we need to see some alternative. To check the lines are perpendicular or not, we need to know what is slope and how to find the slope of a line. Suppose if product of slopes of two lines is equal to -1 then we say the two lines are perpendicular.

##### Difference between intersecting lines and perpendicular lines?

If two lines are intersecting or meeting at a point then we say they are intersecting lines. In intersecting lines, we are not considering the angles i.e. at what angle they are meeting or when they are meeting how much is formed. If two lines are intersecting and if the angle among them is ${ 90 }^{ 0 }$ then we say they are perpendicular lines.

Note:

Perpendicular lines we also say as intersecting lines but intersecting lines may or may not be perpendicular lines.