vector<Reg_Polygon*> get_net (const real triangle_diameter)  Static function 
Returns the net of the Tetrahedron , i.e., the
twodimensional pattern of triangles that can be folded into
a model of a tetrahedron.^{1}
The net lies in the xz plane. The triangles
have enclosing circles of diameter triangle_diameter. The center
of the middle triangle is at the origin.
vector<Reg_Polygon*> vrp = Tetrahedron::get_net(2); for (vector<Reg_Polygon*>::iterator iter = vrp.begin(); iter != vrp.end(); ++iter) { (**iter).draw(); }
This function is used in the nondefault constructor.
See Polyhedron Reference; Regular Platonic Polyhedra; Tetrahedron; Constructors and Setting Functions.
The constructor starts with the net and rotates three of the triangles
about the adjacent vertices of the middle triangle. Currently, all of
the The 
void draw_net (const real triangle_diameter, [bool make_tabs = true ])

Static function 
Draws the net for a Tetrahedron in the xy plane.
The triangles
have enclosing circles of diameter triangle_diameter. The
origin is used as the center of the middle triangle.
The centers of the triangles are numbered.
If the argument make_tabs is used, tabs for gluing and/or sewing a
cardboard model of the Tetrahedron together will be drawn, too.
The dots on the tabs mark where to stick the needle through, when sewing
the model together (I've had good results with sewing).
Tetrahedron::draw_net(3, true);
The net is drawn in the xy plane, because it currently doesn't work to draw it in the xz plane. I haven't gotten around to fixing this problem yet. 