Question

As in the diagram,let A,B,C,D be the centers of the 4 balls in the bottom layer,and A',B',C',D' be the center of the 4 balls in the upper layer.then A,B,C,D and A',B',C',D' are the 4 vertice of the squares of length 2cm,respectively, now the circumscribed circles with centers O and O' of the squares constitue the base of another cylinder,and projecting point A' on the bottom base is the middle point M of arc AB
what is the problem asking me to find?
And how do I show it analytically??...........

Am so confused
It is Issac by the way.......