Question

阴影部分面积多少平方米?

Answer 1

S园＝∏.r²

S长方形＝6.28.r

∵S园＝S长方形

∴∏r²＝6.28r

3.14r＝6.28

∴r＝2

s阴＝s长方形-¼s园

＝6.28*2 - ¼*3.14*2²

＝9.42