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IMO 1989 - Shortlist problems Question 24

IMO Shortlist · IMO 1989 - Shortlist problems

Question 24

(POL 5) For points $A_1,\ldots,A_5$ on the sphere of radius 1, what is the maximum value that $\min_{1\le i,j\le5}A_iA_j$ can take? Determine all configurations for which this maximum is attained. (Or: determine the diameter of any set $\{A_1,\ldots,A_5\}$ for which this maximum is attained.)