A non-zero vector
Consider a plane
(a) N is a normal vector to M.
(b)
(a) Follows from properties (d) and (e) of Theorem 2.12.
(b) Proof is analogous to that for the line discussed in section 2.5.
Given a plane M through P with a normal vector N and
Then,
Proof is analogous to that for the line discussed in Theorem 2.6.
The shortest distance from a point Q to a plane M is
Actually, d is called the distance from Q to M.