theorem Th45:
  for s being Real, p being Point of TOP-REAL 2 holds
  (Rotate(s)).p = 0.TOP-REAL 2 implies p = 0.TOP-REAL 2
  proof
    let s be Real;
    let p be Point of T2;
    |.p.| = |.(Rotate(s)).p.| by Th41;
    hence thesis by TOPRNS_1:23,24;
  end;
