show/hide this revision's text 2 added link to Helly's theorem

If you mean "any four lie in some ball of radius 1", then the same holds for all five points due to Helly Helly's theorem (the unit balls centered in these points must have a common point).

show/hide this revision's text 1

If you mean "any four lie in some ball of radius 1", then the same holds for all five points due to Helly theorem (the unit balls centered in these points must have a common point).