11-5

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

> z1:=-1:z2:=cos(2*t):
z:=(1-s)*z1+s*z2:

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

> with(plottools):
vrml(a,"c:/program files/maple 6/beauty/11-5.wrl",background_color=white);

>