2011 IMO Shortlist A5

Prove that for every positive integer $n$, the set $\{2,3,4, \ldots, 3 n+1\}$ can be partitioned into $n$ triples in such a way that the numbers from each triple are the lengths of the sides of some obtuse triangle.

证明对于每个正整数 $n$，集合 $\{2,3,4, \ldots, 3 n+1\}$ 可以划分为 $n$ 个三元组，使得每个三元组中的数字是某个钝角三角形的边长。