8-06 Construct one half of a torus so its cross-section consists of two disjoint circles

> restart;

> with(plots):

Warning, the name changecoords has been redefined

> a:=tubeplot([cos(t),sin(t),0],t=0..Pi,scaling=constrained,radius=0.4,grid=[30,50]):

> a;

> with(plottools):

> vrml(a,"c:/8-06.wrl",background_color=white);

>