11-9

> 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,color=yellow):
a;

> x:=r*cos(t):y:=r*sin(t):
b:=plot3d([x,y,x^2-y^2],r=0..1,t=0..2*Pi,scaling=constrained,grid=[10,100],color=green):b;

> with(plots):
p:=display(a,b):p;

Warning, the name changecoords has been redefined

> with(plottools):
vrml(p,"c:/program files/maple 6/beauty/11-9.wrl",background_color=white);

>

>