reserve n for Element of NAT,
  i for Integer,
  a, b, r for Real,
  x for Point of TOP-REAL n;

theorem Th9:
  the carrier of Tcircle(x,r) = Sphere(x,r)
proof
  [#]Tcircle(x,r) = Sphere(x,r) by PRE_TOPC:def 5;
  hence thesis;
end;
