## 4A(tan(a/2)+tan(b/2)+tan(c/2))<=9R^2

Prove that in a triangle: $4A\cdot\left(\tan\frac {\alpha}2+\tan\frac {\beta}2+\tan\frac {\gamma}2\right)\le 9R^2$ where $A$ is the area of the triangle and $R$ is the radius of the circumcircle.