12寸的披萨的体积是=3.1415926X6X6X2=226.1946711立方寸
9寸的披萨的体积是=3.1415926X4.5X4.5X1.5=95.42587685立方寸
6寸的披萨的体积是=3.1415926X3X3X1.5=42.41150082立方寸
1个9寸+2个6寸的体积是95.42587685+42.41150082X2=180.2488785立方寸,比12寸的体积小了45.94579261立方寸,还是不划算。
而2个9寸+1个6寸的体积是95.42587685X2+42.41150082=233.2632545立方寸,这还差不多。