reserve A,B,C,D,E,F,G for Point of TOP-REAL 2;

theorem Th2:
  0 <= angle(A,B,C) < 2*PI
  proof
    angle(A,B,C) = angle(euc2cpx(A),euc2cpx(B),euc2cpx(C)) by EUCLID_3:def 4;
    hence thesis by COMPLEX2:70;
  end;
