Disks
Find the volume of the solid obtained by rotating about the x-axis the area under the curve f(x)=sqrt(5x) from x=0 to x=1.
> restart;
> f:=sqrt(5*x);
The region to be rotated is
> L:=[[1,0],[1,f(1)]]:
> plot({L,f},x=0..1);
The graph of the volume is
> with(plots);
> tubeplot([x,0,0],x=0..1,radius=f(x),axes=normal);
The volume is given by
> Int(Pi*f^2,x=0..1);
> value(%);