I didn't success to solve the intgral of this function
x(cos(x))/((sin(x))^3) dx
Start by integrating by parts:
$\displaystyle u = x$
$\displaystyle du = dx$
$\displaystyle dv = \frac{\cos x}{\sin^3 x} dx$
$\displaystyle v = -\frac{1}{2 \sin^2 x}$
$\displaystyle \int \frac{x \cos x}{\sin^3 x} dx = -\frac{x}{2 \sin^2 x} + \int \frac{1}{2 \sin^2 x} dx$