11-14 Describe how 4 identical pipes are joined together symmetrically.

> restart;:

> r:=1/sqrt(2):

> with(plots):with(plottools):

Warning, the name changecoords has been redefined

> x:=cos(t):

> y:=sin(t):

> u:=x*r:

> z:=(1-s)*2+s*u:

> a1:=plot3d([x,y,z],t=-Pi/3..Pi/3,s=0..1,scaling=constrained,grid=[30,8]):

> a2:=rotate(a1,0,0,2*Pi/3):

> a3:=rotate(a1,0,0,4*Pi/3):

> a:=display(a1,a2,a3):

> b1:=reflect(a,[[0,0,0],[1,0,r],[1,1,r]]):

> b2:=rotate(b1,0,0,2*Pi/3):

> b3:=rotate(b1,0,0,4*Pi/3):

> p:=display(a,b1,b2,b3):

> p;

> vrml(p,"c:/Program Files/Maple 6/beauty/11-14.wrl",background_color=white);

>