/ 2 2 2 2 \
| 2*cos (3*x) 6*sin (3*x) 8*cos (3*x)*sin (3*x)|
27*|-1 - ------------- + ------------- + ---------------------|*cos(3*x)
| 2 2 2 |
| 1 + sin (3*x) 1 + sin (3*x) / 2 \ |
\ \1 + sin (3*x)/ /
------------------------------------------------------------------------
2
1 + sin (3*x)
$$\frac{27 \cos{\left (3 x \right )}}{\sin^{2}{\left (3 x \right )} + 1} \left(-1 + \frac{6 \sin^{2}{\left (3 x \right )}}{\sin^{2}{\left (3 x \right )} + 1} - \frac{2 \cos^{2}{\left (3 x \right )}}{\sin^{2}{\left (3 x \right )} + 1} + \frac{8 \sin^{2}{\left (3 x \right )} \cos^{2}{\left (3 x \right )}}{\left(\sin^{2}{\left (3 x \right )} + 1\right)^{2}}\right)$$