There is a plane 3x - y +7z = 21
Find a vector parallel, and a vector perpendicular to this plane.
A plane has a normal(perpendicular) vector of n=<a,b,c>
To find a parallel vector, find a vector which is perpendicular to the normal.
The dot product of this vector and the normal vector is 0.
Intuitively, there should be a quick one to come up with.