Problem $4$: $(10$ points$)$ Find the volume of the solid obtained by rotating the region bounded by $y=sinx,y=0,x=0$ and $x=,$ about the $x-$axis.Problem $5$: $(10$ points$)$ Find the volume of the solid obtained by rotating the region bounded by $y=e^x,y=e^{\frac{1}{2}x},x=0,$ and $x=2,$ about the $x-$axis.