text: how much do the two balls in th square overlap on the x axis? is there a formula for this this type question? assuming that the diameter of each ball is one meter. as seen in this picture http://www.inf.u-szeged.hu/~pszabo/packings/circles2.html the centers of the circles are 1/2 m in from the side of the square. the small square has a diagonal of 1 m. the side of that square is sqrt(2)/2 m.   that makes the side of the large square 1+sqrt(2)/2.  let x be the overlap, then 2 - x  = 1+sqrt(2)/2  x = 1 - sqrt(2)/2