MathDB
There exists a triangle [Iran Second Round 1996]

Source:

November 25, 2010
inequalitiesinequalities proposed

Problem Statement

Let a,b,ca, b, c be real numbers. Prove that there exists a triangle with side lengths a,b,ca, b, c if and only if 2(a4+b4+c4)<(a2+b2+c2)2.2(a^4 + b^4 + c^4) < (a^2 + b^2 + c^2)^2.