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MathNet 2015-part-02 — 191 problems (EN–VI) Question 2

Math Olympiad Vault · MathNet 2015-part-02 — 191 problems (EN–VI)

Question 2

Let $ABC$ be an acute-angled triangle with altitudes $AD$, $BE$, and $CF$. Let $H$ be the orthocentre, that is, the point where the altitudes meet. Prove that
$$
\frac{AB \cdot AC + BC \cdot BA + CA \cdot CB}{AH \cdot AD + BH \cdot BE + CH \cdot CF} \le 2.
$$