Construct one half of a torus so its cross-section consists of two intersecting circles.

> restart:

> a:=3:

> b:=4:

> c:=sqrt(a^2+b^2):

> r:=c+a*cos(t):

> x:=r*cos(s):

> y:=r*sin(s):

> z:=a*sin(t):

> u:=solve(b*z=a*x,s):

> h:=plot3d([x,y,z],s=-u..u,t=0..2*Pi,scaling=constrained,grid=[30,30]):

> h;

> with(plottools):

> vrml(h,"c:/042/13/13-7.wrl",background_color=white);
 

maple