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Spanish Mathematical Olympiad 2005, Problem 3

Source: 2005 Spanish Mathematical Olympiad

July 17, 2017
geometry

Problem Statement

We will say that a triangle is multiplicative if the product of the heights of two of its sides is equal to the length of the third side. Given ABCXYZABC \dots XYZ is a regular polygon with nn sides of length 11. The n3n-3 diagonals that go out from vertex AA divide the triangle ZABZAB in n2n-2 smaller triangles. Prove that each one of these triangles is multiplicative.