Note on the number of obtuse angles in point sets
In 1979 Conway, Croft, Erd\H{o}s and Guy proved that every set SS of nn points in general position in the plane determines at least n3/18−O(n2) obtuse angles and also presented a special set of nn points to show the upper bound 2n3/27−O(n2) on the minimum number of obtuse angles…