theorem Th66:
  |.z*'.| = |.z.|
proof
A1: z*' = [*Rea z, -Im1 z, -Im2 z, -Im3 z*] by Th36; then
A2: Im1 z*' = - Im1 z by Th16;
A3: Im2 z*' = - Im2 z by A1,Th16;
  Im3 z*' = - Im3 z by A1,Th16;
  hence thesis by A1,A2,A3,Th16;
end;
