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IMO 2003 — Complete Shortlist Question 11

IMO Shortlist · IMO 2003 — Complete Shortlist

Question 11

Every point with integer coordinates in the plane is the centre of a disc with radius 1/1000.

(1) Prove that there exists an equilateral triangle whose vertices lie in different discs.

(2) Prove that every equilateral triangle with vertices in different discs has side-length greater than 96.