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 Th5:
  cpx2euc(x1+x2*<i>)= |[x1,x2]|
proof
  Re (x1+x2*<i>)=x1 by COMPLEX1:12;
  hence thesis by COMPLEX1:12;
end;
