,
r n
r⋅∧
 = d
(as
1)
∧n n
∧⋅
=
… (2)
This is the vector form of the equation of the plane Cartesian form
Equation (2) gives the vector equation of a plane, where nˆ  is the unit vector normal to
the plane Let P(x, y, z) be any point on the plane Then
OP
uuur
 = 
ˆ
ˆ
ˆ
r
x i
y j
= + +z k
r
Let l, m, n be the direction cosines of nˆ