[math-fun] Tetranacci Tetrahedron

Let t^2 =1.92756 be the tetranacci constant.    Build a tetrahedron with edgelengths t^0 opposite t^3 t^1 opposite t^1 t^2 opposite t^2 This has 4 similar triangles of 2 sizes.   If this tetrahedron is rolled on its edges, it only reaches 12 different orientations. -Ed Pegg Jr