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Easy but nice inequality

Source: III Caucasus Mathematical Olympiad

March 17, 2018
inequalities

Problem Statement

Let a,b,ca, b, c be the lengths of sides of a triangle. Prove the inequality (a+b)ab+(a+c)ac+(b+c)bc(a+b+c)2/2.(a+b)\sqrt{ab}+(a+c)\sqrt{ac}+(b+c)\sqrt{bc} \geq (a+b+c)^2/2.