?$ ①12×12 - 3.14×(12\div 2)^2 $?
?$= 144 - 3.14×36$?
?$ = 144 - 113.04 $?
?$= 30.96($?平方厘米?$)$?
?$ ②12×12 - 3.14×(12\div 2\div 2)^2×4$?
?$ = 144 - 3.14×9×4 $?
?$= 144 - 113.04 $?
?$= 30.96($?平方厘米?$)$?
?$ ③12×12 - 3.14×(12\div 3\div 2)^2×9$?
?$ = 144 - 3.14×4×9 $?
?$= 144 - 113.04 $?
?$= 30.96($?平方厘米?$)$?