(1)72×2÷(7.5+4.5)×3÷2
=12×3÷2
=18平方厘米
(2)3.14×【(4+2)/2×(4+2)/2-4/2×4/2-2/2×2/2】×1/2
=3.14×【9-4-1】×1/2
=3.14×2
=6.28平方厘米