The shaded part in the above figure consists of eight green figures, the area of which is1/4, the area of a circle with a radius of 16÷2-1/2, and the area of a square with a side length of 16÷2.

So the shadow area =(3. 14×8? × 1/4-8? × 1/2)×8 =(50.24-32)×8 = 18.24×8 = 145.92 cm2。