Name: Anonymous 2007-10-08 15:03
On the bottom of the conus are laying three spheres of the same size, everyone of them is in contact with the other two. Ontop of them there is a forth sphere of the same size. All of the spheres are in contact with the side of the conus. Find the distance from the tip of the topmost sphere to the bottom of the conus and the axial section's vertex. The radius of the sphere is r.