reserve z,z1,z2 for Complex;
reserve r,x1,x2 for Real;
reserve p0,p,p1,p2,p3,q for Point of TOP-REAL 2;

theorem Th11:
  cpx2euc(-z)= -cpx2euc(z)
proof
  -cpx2euc(z) =|[-(Re z), -(Im z)]| by EUCLID:60;
  hence thesis by Th10;
end;
