8-04

> restart;

> with(plots):

> k:=5:

> r:=3+cos(t):

> x:=r*cos(s):y:=r*sin(s):z:=sin(t):

> s:=u+v:

> t:=k*u:

> a:=plot3d([x,y,z],u=0..2*Pi,v=0..Pi/k,scaling=constrained,color=yellow,grid=[100,20]):

> b:=plot3d([x,y,z],u=0..2*Pi,v=Pi/k..2*Pi/k,scaling=constrained,color=blue,grid=[100,20]):

> display(a,b);

>