>

restart;

>	a:=2;b:=5;c:=sqrt(a^2+b^2);

>

t:=3*s;

>	with(plots);

Warning, the name changecoords has been redefined

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

>	x:=r*cos(s+q);y:=r*sin(s+q);

>	p1:=plot3d([x,y,z],s=0..2*Pi,q=0..Pi/3,scaling=constrained,grid=[50,50],color=yellow):

>	p2:=plot3d([x,y,z],s=0..2*Pi,q=Pi/3..2*Pi/3,scaling=constrained,grid=[50,50],color=green):

>	display(p1,p2);

>