10
© NCERT
not to be republished
 MATHEMATI CS
480
Therefore, (2) gives
ˆ
ˆ
ˆ
ˆ
ˆ
ˆ
(
) (
)
x i
y j
z k
l i
m j
n k
d
+
+
⋅
+
+
=
i e ,
 lx + my + nz = d (3)
This is the cartesian equation of the plane in the normal form