Chapter 11, Problem 17P

Define x as a symbolic variable and create the symbolic expression

$S=\frac{{\cos }^{2}x}{1+{\sin }^{2}x}$

Plot S in the domain $0\le x\le \pi$ and calculate the integral $I={\displaystyle {\int }_0^{\pi }\frac{{\cos }^{2}x}{1+{\sin }^{2}x}}dx$ .