Intersecting Lines – Definition, Properties, Examples

What are Intersecting Lines?

When two or more lines cross each other in a plane, they are called intersecting lines. The intersecting lines share a common point, which exists on all the intersecting lines, and is called the point of intersection

Here, lines P and Q intersect at point O, which is the point of intersection. 

point of intersection

In the given image below, there are many straight lines crossing each other and intersecting at the common point P. 

intersecting at the common point

Properties of intersecting lines

  • The intersecting lines (two or more) meet only at one point always. 
  • The intersecting lines can cross each other at any angle. This angle formed is always greater than $0^\circ$  and less than $180^\circ$ . 
  • Two intersecting lines form a pair of vertical angles. The vertical angles are opposite angles with a common vertex (which is the point of intersection). 

Here, $\angle a$ and $\angle c$ are vertical angles and are equal.  Also, $\angle b$ and $\angle d$ are vertical angles and equal to each other. 

$\angle a + \angle d =$ straight angle $= 180^\circ$

properties of intersecting lines

Intersecting Lines in Real Life

  • Crossroads: Two roads (consider as straight lines) meeting at a common point make crossroads.
  • Scissors: The two arms of the scissors form intersecting lines.
Intersecting lines in real life
Fun Facts
1. The lines that intersect at more than one point are curved lines and not straight.
2. Two lines that intersect at exactly 90o angle to each other (forming a perpendicular) are called perpendicular lines. Thus, perpendicular lines are a special case of intersecting lines.