Given the partition $\{0,\,\frac{\pi}{4},\,\frac{\pi}{2},\,\frac{3\pi}{4},\,\pi\}$, find $L(P)$ and $U(P)$ for the integral $\int_0^{\pi}\sin(x)\,dx$.

Problem: 

Given the partition $\{0,\,\frac{\pi}{4},\,\frac{\pi}{2},\,\frac{3\pi}{4},\,\pi\}$, find $L(P)$ and $U(P)$ for the integral $\int_0^{\pi}\sin(x)\,dx$.

Answer: 

$L(P)=\frac{\pi\sqrt{2}}{4}$ and $U(P)=\frac{\pi\,(2+\sqrt{2})}{4}$