Given : the lines and _.

To prove : the lines are at right angles.

Formula used : If the lines are = = and = =

then the angle between the lines ‘θ’ is given by

θ =

The lines and _.

Here p = 7 , q = -5 , r = 1 and l = 1 , m = 2 , n = 3

θ = =

θ = = = 90°

θ = 90°

The Lines and are at right angles.