This is an image showing the a vertex view of a tetrahedron with three spheres. The smallest Sphere is tagent to the faces of the tetrahedron, the middle sphere is tangent to the edges of the tetrahedron and the Tetrahedrons vertexes correspond to the largest sphere. * THIS GRAPHIC IS IN THE PUBLIC DOMAIN AND CAN BE USED FOR ANY PURPOSE WITHOUT ATTRIBUTION (although it is appreciated) Click Image to Download