theorem Th10:
  |[Re (-z),Im (-z)]|=|[-(Re z), -(Im z)]|
proof
  (|[Re (-z),Im (-z)]|)`2=Im (-z) by EUCLID:52;
  then
A1: (|[Re (-z),Im (-z)]|)`2=-(Im z) by COMPLEX1:17;
  (|[Re (-z),Im (-z)]|)`1=Re (-z) by EUCLID:52;
  then (|[Re (-z),Im (-z)]|)`1=-(Re z) by COMPLEX1:17;
  hence thesis by A1,EUCLID:53;
end;
