If is a normal vector of a plane, then it is perp. to every vector on the plane right? Let be vectors on the plane.
Then .
Then shouldnt ?
when we refer to , we are referring to the (vector) equation of a plane. in this "construct", is a vector in the plane, but and are actually vectors beginning at the origin whose terminal points are points in the plane, so individually, they are not necessarily perpendicular to the normal vector