Chapter 11, Problem 18P

Define x as a symbolic variable and create the symbolic expression:

$S=\frac{6{\sin }^{2}x}{{(3\sin x+1)}^2}$

Plot S in the domain $0\le x\le \pi$ and calculate the integral

$I={\displaystyle {\int }_0^{\pi }\frac{6{\sin }^{2}x}{{(3\sin x+1)}^2}}$