# 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.

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

## 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 $= 180^\circ$