a, b, c - the side lengths of a triangle

k - a positive real number

$\displaystyle \frac{a^{k}}{(b+c)^{2}}+\frac{b^{k}}{(a+c)^{2}}+\f rac{c^{k}}{(b+a)^{2}}\geq \frac{1}{2}(\frac{a^{k}}{a^{2}+bc}+\frac{b^{k}}{b^ {2}+ac}+\frac{c^{k}}{c^{2}+ba})$

I observed that: $\displaystyle (b+c)^{2}+(a+c)^{2}+(b+a)^{2}=2(a^{2}+bc+b^{2}+ac+ c^{2}+ba)$, so CBS inequality seems a good idea, but what I tried to do didn't help me ._.

I want some indications. Thanks in advance.