> with(plots):with(plottools):

> x:=cos(t):y:=sin(t):

> z1:=-1.5:z2:=x:z:=(1-s)*z1+s*z2:

> a:=plot3d([x,y,z],s=0..1,t=0..2*Pi,scaling=constrained,grid=[5,50]):

> b:=reflect(a,[[0,0,0],[1,0,1],[2,-1,2]]):

> c:=display(a,b):

> c;

> vrml(c,"C:/My Documents/trfa/wrl/11-2.wrl",background_color=white);

>