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;
