v1' = center (back_face c)
v2' = Face.v0 (back_face c)
v3' = Face.v1 (back_face c)
- fv' = rotate cwy $ rotate cwy $ (Tetrahedron.fv (tetrahedron0 c))
+ fv' = rotate cwy $ rotate cwy $ Tetrahedron.fv (tetrahedron0 c)
tetrahedron9 :: Cube -> Tetrahedron
tetrahedron9 c =