Show that each of the following pairs of planes are at right angles:
(i) 3x + 4y - 5z = 7 and 2x + 6y + 6z + 7 = 0
(ii) x - 2y + 4z = 10 and 18x + 17y + 4z = 49
To find angle in Cartesian form, for standard equation of planes
For θ=90°, cos90°=0
(i)On comparing with the standard equation of a plane
=0=RHS
Hence proved that the angle between planes is 90°.
(ii) On comparing with the standard equation of a plane
=0=RHS
Hence proved that angle between planes is 90°.