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Acute triangle

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anemone

MHB POTW Director
Staff member
Feb 14, 2012
3,838
In an acute triangle $ABC$, prove that $\dfrac{\cos A}{\cos (B-C)}+\dfrac{\cos B}{\cos (C-A)}+\dfrac{\cos C}{\cos (A-B)}\ge \dfrac{3}{2}$.