> restart:

> 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]):

> with(plots):

> with(plottools): to use reflect,rotate,translate

> b:=reflect(a,[[0,0,0],[1,0,1],[2,-1,2]]): 在平面x=z上找三點,depe

ndent

> c:=display(a,b):

> vrml(c,"c:/My documents/87124/11/11-02.wrl",background_color=white):

> display(c);

>