Rectangle ISPE is drawn with IS > 3PS, IS = 20, EI = 3. There are two circles centered at P and S such that the two congruent circles are tangent to each other. A semicircle with center at N, which is the midpoint of EI, and radius 2, is drawn so that it is tangent to the rectangle and does not cross PE or IS. Another circle circumscribes the whole figure. What is the radius of this circle?
