Question

第六题怎么做?

Answer 1

S=S大圆-S小圆=πR2-πr2=（144-64）π=80π cm2≈251cm2

Answer 2

思路：大圆面积-小圆面积=阴影面积
3.14x12x12-3.14x8x8
=3.14x144-3.14x64
=3.14x（144-64）
=3.14x80
=251.2