> restart;
> x:=r*cos(t);
> y:=r*sin(t);
> r:=cos(t);
> p1:=plot3d([x,y,z],t=-Pi/2..Pi/2,z=-sqrt(1-r^2)..sqrt(1-r^2),

   scaling=constrained,style=patchnogrid,color=green):
> p2:=plot3d([s*x,s*y,sqrt(1-s*s*r*r)],t=-Pi/2..Pi/2,s=0..1,

   scaling=constrained,style=patchnogrid,color=red):
> p3:=plot3d([s*x,s*y,-sqrt(1-s*s*r*r)],t=-Pi/2..Pi/2,s=0..1,

   scaling=constrained,style=patchnogrid,color=red):
> with(plots):
> display(p1,p2,p3);
　

> restart;
> x:=r*cos(t);
> y:=r*sin(t);
> r:=cos(t);
> plot3d([x,y,z],t=-Pi/2..Pi/2,z=-sqrt(1-r^2)..sqrt(1-r^2),scaling=constrained);
　

> with(plottools):
> p:=Pi/2;
> x1:=cos(t);
> y1:=sin(t);
> x2:=cos(t+p);
> y2:=sin(t+p);
> z:=Pi/2-t;
> q:=expand((1-u)*[z*x1,z*y1,z]+u*[z*x2,z*y2,z],scaling=constrained):
> p1:=plot3d(q,u=0..1,t=0..Pi/2):
> p2:=display(rotate(p1,0,0,p),color=green,style=patchnogrid):
> p3:=display(rotate(p1,0,0,2*p),color=blue,style=patchnogrid):
> p4:=display(rotate(p1,0,0,3*p),color=yellow,style=patchnogrid):
> p5:=plot3d(q,u=0..1,t=0..Pi/2,

   scaling=constrained,color=red,style=patchnogrid):
> display(p2,p3,p4,p5);

> restart;
> x1:=1;
> y1:=(1-u)*1+u*(-1);
> x2:=cos(t)*x1-sin(t)*y1;
> y2:=sin(t)*x1+cos(t)*y1;
> z:=t;
> p1:=plot3d([(Pi-t)*x2,(Pi-t)*y2,z],u=0..1,t=0..Pi,

   scaling=constrained,style=patchnogrid):
> with(plottools):
> p2:=display(rotate(p1,0,0,Pi/2),color=green):
> p3:=display(rotate(p1,0,0,Pi),color=blue):
> p4:=display(rotate(p1,0,0,3*Pi/2),color=yellow):
> p5:=plot3d([(Pi-t)*x2,(Pi-t)*y2,z],u=0..1,t=0..Pi,

   scaling=constrained,color=red,style=patchnogrid):
> with(plots):
> display(p2,p3,p4,p5);

> restart;
> with(plots):
> with(plottools):
> restart;
> with(plots):
> x:=r*cos(t);
> y:=r*sin(t);
> p1:=plot3d([x,y,-x^2+1/2],r=0..1,t=0..2*Pi,

   scaling=constrained,grid=[11,51],color=yellow):
> p2:=plot3d([x,y,y^2-1/2],r=0..1,t=0..2*Pi,

   scaling=constrained,grid=[11,51],color=blue):
> display(p1,p2);

> restart;
> with(plots):
> x:=cos(t);
> y:=sin(t);
> p1:=tubeplot([x,y,0],t=0..2*Pi,radius=0.2,

   scaling=constrained,color=red,style=patchnogrid):
> p2:=tubeplot([0+0.6,x+0.6,y+0.6],t=0..2*Pi,radius=0.2,

   scaling=constrained,color=green,style=patchnogrid):
> p3:=tubeplot([y+0.6,0+0.6,x-0.6],t=0..2*Pi,radius=0.2,

   scaling=constrained,color=blue,style=patchnogrid):
> display(p1,p2,p3);

> restart;
> with(plots):
> x:=5*cos(t);
> y:=3*sin(t);
> p1:=tubeplot([x,y,0],t=0..2*Pi,radius=0.5,

   scaling=constrained,color=red,style=patchnogrid):
> p2:=tubeplot([0,x,y],t=0..2*Pi,radius=0.5,

   scaling=constrained,color=green,style=patchnogrid):
> p3:=tubeplot([y,0,x],t=0..2*Pi,radius=0.5,

   scaling=constrained,color=blue,style=patchnogrid):
> display(p1,p2,p3);