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 :
(1) a21+b21+c21+a′21+b′21+c′21=0
(2) a21−b21−c21+a′21−b′21−c′21=0
(3) a21+b21+c21−a′21−b′21−c′21=0
(4) a21−b21+c21−a′21+b′21−c′21=0