If the three points were on the same
line, then there will be many planes that will contain them
(Fig 11 15) These planes will resemble the pages of a book where the
line containing the points R, S and T are members in the binding
of the book Cartesian form
Let (x1, y1, z1), (x2, y2, z2) and (x3,  y3,  z3) be the coordinates of the points R, S and T
respectively