theorem Th32:
  for A be being_line Subset of AS holds a,a // A
proof
  let A be being_line Subset of AS;
  consider p,q such that
A1: p<>q and
A2: A=Line(p,q) by Def3;
  a,a // p,q by Th2;
  hence thesis by A1,A2;
end;
