Angle between planes in Vector Form

Given

Plane 1: r.n1 = d1.

Plane 2: r.n2 = d2.

cos θ = (n1.n2)/[ |n1| |n2|]

Condition of perpendicularity of planes

(n1.n2) = 0

Condition of parallelism of planes

n1 = λn2


Revision topic of
THREE DIMENSIONAL GEOMETRY