In this demonstration, it is possible to change the positions of the
three vectors, A, colored red, B, colored green, and C, colored yellow,
by clicking and dragging the heads of the vectors. This will move each
of them within the viewing plane. To change the viewing plane, select Rotate from the Tools menu and click and drag anywhere in the
viewing window. The plane given by A + sB + tC, with s and t each going
from 0 to 1, is shown in gray. The plane through the origin parallel to
this plane, given by sB + tC, is also shown in gray.