Solution: radius × radius =24/2= 12 cm2.
Trapezoidal area: (radius +2× radius )× radius ÷2=( 1+2)× radius× radius ÷2=3× 12÷2= 18 cm2;
Half area of the semicircle: 3. 14× radius× radius ÷ 2 ÷ 2 = 3.14×12 ÷ 2 = 9.42 square centimeters.
Area of a blank triangle: radius × radius ÷2= 12÷2=6 cm2.
Nail shadow area:18-9.42 = 8.58cm2.
B Shadow area: 9.42-6 = 3.42cm2..
Therefore, the area of shadow A is larger than that of shadow B: 8.58-3.42=5. 16 cm2.