Therefore, the distance from O to CD perpendicular to OE is OE, which is equal to the radius, half of AB, and OE=5.

(2) First, find the area of the right-angled trapezoid AOED minus the area of a quarter circle.

AO=5 ED=5+ 3/5 root number 3 OE=5 shadow area =25+ 6/25 root number 3 4 25π.