[b]Definition:[/b] Any finite number of vectors are called coplanar vectors if they lie on the same plane or parallel planes.[br]If the vectors are coplanar them we can always draw a parallel plane to all of them. Similarly, a finite number of vectors are said to be non-coplanar if they do not lie on the same plane or on the parallel planes. In this case we cannot draw a single plane parallel to all of them.[br][b]Theorem[/b]: If [math]a^{\rightarrow},b^{\rightarrow}[/math] and [math]c^{\rightarrow}[/math] be any three non-zero and non-coplanar space vectors such that [math]xa^{\rightarrow}+yb^{\rightarrow}+zc^{\rightarrow}=0[/math] then x = y = z = 0