reserve p1, p2 for Point of TOP-REAL 2,
  C for Simple_closed_curve,
  P for Subset of TOP-REAL 2;

theorem Th6:
  for r being Real holds Rotate(-r) = Rotate(2*PI-r)
proof
  let r be Real;
  now
    let p be Point of TOP-REAL 2;
    thus (Rotate(2*PI-r)).p = |[Re Rotate(p`1+(p`2)*<i>,2*PI-r),Im Rotate(p`1+
    (p`2)*<i>,2*PI-r)]| by Def3
      .= |[Re Rotate(p`1+(p`2)*<i>,-r),Im Rotate(p`1+(p`2)*<i>,2*PI-r)]| by Th5
      .= |[Re Rotate(p`1+(p`2)*<i>,-r),Im Rotate(p`1+(p`2)*<i>,-r)]| by Th5;
  end;
  hence thesis by Def3;
end;
