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 Th9:
  euc2cpx(p1+p2)=euc2cpx(p1)+euc2cpx(p2)
proof
  euc2cpx(p1+p2)= p1`1+p2`1+(p1`2+p2`2)*<i> by Th8;
  hence thesis;
end;
