Two systems of rectangular axes have the same origin. If a plane cuts them at distance a, b, c and a' , b', c' from the origin, then

The planes are   xa+yb+zc=1 and xa′+yb′+zc′=1Since the perpendicular distance of the origin on the planes is same, therefore−11a2+1b2+1c2=−11a′2+1b′2+1c′2or  1a2+1b2+1c2−1a′2−1b′2−1c′2=0