Hadwiger-Finsler inequalityHadwigerFinslerInequality2002-06-06 11:31:342002-12-26 18:58:06Theorem% this is the default PlanetMath preamble. as your knowledge
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% define commands hereIn a triangle with sides $a$, $b$, $c$ and an area $A$ the following inequality holds:
$$a^2+b^2+c^2\geq (a-b)^2+(b-c)^2+(c-a)^2 +4A\sqrt{3}.$$