4÷2=2厘米 3÷2=1.5厘米
( 3.14×2×2×1/2-4×2×1/2)+(3.14×1.5×1.5×1/2-3×1.5×1/2)
=(6.28-4)+(7.065-2.25)
=2.28+4.815
=7.095平方厘米