 reserve S for satisfying_Tarski-model TarskiGeometryStruct;
 reserve a, b, c, d, e, f, o, p, q, r, s,
    v, w, u, x, y, z, a9, b9, c9, d9, x9, y9, z for POINT of S;

:: (which we also assume) and then apply the theorem that complements
:: of congruent angles are congruent.  Hence Tarski's axiom.

  proof
    S is satisfying_SAS;
    hence thesis;
  end;
