In $\Delta ABC$,show that $$\tan{\frac{A}{2}}+\tan{\frac{B}{2}}+\tan{\frac{C}{2}}-\frac{\sqrt{3}-1}{8}\csc{\frac{A}{2}}\csc{\frac{B}{2}}\csc{\frac{C}{2}}\le 1$$
I tried also $$\left(\tan{\frac{A}{2}}+\tan{\frac{B}{2}}+\tan{\frac{C}{2}}\right)^2\ge 3\left(\tan{\frac{A}{2}}\tan{\frac{B}{2}}+\tan{\frac{A}{2}}\tan{\frac{C}{2}}+\tan{\frac{C}{2}}\tan{\frac{B}{2}}\right)=3,$$ but we get there something, which impossible to kill during a competition.