# What is the angle between two lines whose direction ratios satisfy following equations?

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Find the angle between two lines whose **direction ratios** satisfy #2l-m+2n=0# and #mn+nl+lm=0#

Find the angle between two lines whose **direction ratios** satisfy

##### 1 Answer

The two lines are perpendicular to each other.

#### Explanation:

Let the direction cosines of the two lines be

**.............................(1)** and

**.............................(2)**

Note that if

and the angle

From (1), we get

or

i.e either

if

and if

and

=

=

Hence the two lines are perpendicular to each other.