> restart;
> y:=r*cos(t);
> z:=r*sin(t);
> x:=y^2+z^2;
> p1:=plot3d([x,y,z],r=abs(cos(t))..1,t=0..2*Pi,

    scaling=constrained,color=red,grid=[31,101]):
> with(plots):
> x:=r*cos(t);
> z:=r*sin(t);
> y:=x^2+z^2;
> p2:=plot3d([x,y,z],r=abs(cos(t))..1,t=0..2*Pi,

    scaling=constrained,color=green,grid=[31,101]):
> p3:=display(p1,p2):
> with(plottools):
> p4:=reflect(p3,[0,0,0]):
> display(p3,p4);
　

> restart;
> with(plots):
> p1:=tubeplot([1,-1,t],t=-1..1,grid=[5,51]):
> with(plottools):
> p2:=rotate(p1,2*Pi/3,[[0,0,0],[1,1,1]]):
> p3:=rotate(p1,4*Pi/3,[[0,0,0],[1,1,1]]):
> display(p1,p2,p3);
　

> restart;
> with(plots):
> p1:=tubeplot([t,0,0],t=-1..1,radius=t,grid=[5,51]):
> with(plottools):
> p2:=rotate(p1,0,Pi/2,0):
> p3:=rotate(p1,0,0,Pi/2):
> display(p1,p2,p3);
　

> restart;
> with(plots):
> p1:=tubeplot([-t,-t,-t],t=0..1,radius=sqrt(6)*t,grid=[5,51],

    scaling=constrained,color=red):
> p2:=tubeplot([-t,t,t],t=0..1,radius=sqrt(6)*t,grid=[5,51],

    scaling=constrained,color=green):
> p3:=tubeplot([t,-t,t],t=0..1,radius=sqrt(6)*t,grid=[5,51],

    scaling=constrained,color=blue):
> p4:=tubeplot([t,t,-t],t=0..1,radius=sqrt(6)*t,grid=[5,51],

     scaling=constrained,color=yellow):
> display(p1,p2,p3,p4);

> restart;
> with(plots):
> p1:=tubeplot([t,t,t],t=0..1,radius=sqrt(3/2)*t,grid=[5,51],

    scaling=constrained,color=red):
> p2:=tubeplot([-t,t,t],t=0..1,radius=sqrt(3/2)*t,grid=[5,51],

    scaling=constrained,color=green):
> p3:=tubeplot([t,-t,t],t=0..1,radius=sqrt(3/2)*t,grid=[5,51],

    scaling=constrained,color=blue):
> p4:=tubeplot([-t,-t,t],t=0..1,radius=sqrt(3/2)*t,grid=[5,51],

    scaling=constrained,color=yellow):
> with(plottools):
> q1:=display(p1,p2,p3,p4):
> q2:=reflect(q1,[0,0,0]):
> display(q1,q2);
　

> restart;
> x:=r*2*cos(t);
> y:=r*sin(t);
> z:=4-y^2;
> p1:=plot3d([x,y,z],r=0..1,t=0..2*Pi,

    scaling=constrained,color=red,grid=[11,101]):
> z:=x^2+3*y^2;
> p2:=plot3d([x,y,z],r=0..1,t=0..2*Pi,

    scaling=constrained,color=green,grid=[11,101]):
> with(plots):
> display(p1,p2);