<s>[INST] Nan wishes to draw a set of 6 non-overlapping circles in a plane, all of radius 2. He will be satisfied if each pair of circles has a non-empty intersection. If he draws the circles so that their centres lie on a circle, then what is the minimum radius of the circle on which he can locate the centres of the 6 circles such that all 6 circles are non-overlapping and each pair of circles has a non-empty intersection?[/INST]