With usual notations, in $\triangle \mathrm{ABC}$, the lengths of two sides are 10 cm and 9 cm respectively. If angles $\mathrm{A}, \mathrm{B}, \mathrm{C}$ are in A.P. then perimeter of $\triangle \mathrm{ABC}$ is

$$ \int \frac{\mathrm{d} x}{\mathrm{e}^x-1}= $$

The maximum value of $x^{2 / 3}+(x-2)^{2 / 3}$ is

$$ \int\left(\frac{x-3}{x^2+9}\right)^2 d x= $$