Then the area of the semicircle is1/2uighur r 2 =1/2uighur * 2 2 = 2uighur.
Two small semicircles add up to a circle, so the radius of the two small semicircles is 4/2/2 = 1.
So the sum of the areas of two small semicircles is the area of the circle, which is r 2 = u.
So the shadow area is: 2-5 = 5.