reserve a, b, c, d, r, s for Real,
  n for Element of NAT,
  p, p1, p2 for Point of TOP-REAL 2,
  x, y for Point of TOP-REAL n,
  C for Simple_closed_curve,
  A, B, P for Subset of TOP-REAL 2,
  U, V for Subset of (TOP-REAL 2)|C`,
  D for compact with_the_max_arc Subset of TOP-REAL 2;

theorem Th17:
  for r being non negative Real
  for p being Point of TOP-REAL n holds p is Point of Tdisk(p,r)
proof
  let r be non negative Real;
  let p be Point of TOP-REAL n;
A1: the carrier of Tdisk(p,r) = cl_Ball(p,r) by BROUWER:3;
  |. p-p .| = 0 by TOPRNS_1:28;
  hence thesis by A1,TOPREAL9:8;
end;
