VITEEE 2015 Paper

Given lines are
x = my + n, z = py + q
and x = m' y + n', z = p' y + q'
Above equations can be rewritten as

x−n

m

=

y+0

1

=

z−q

p

and

x−n′

m′

=

y−0

1

=

z−q′

p′

Lines will be perpendicular,
if mm' + 1 + pp' = 0
⇒ mm' + pp' = -1