看图列式子(六年级的) 一个是半圆环,内圆为6cm ,外圆为10cm,都是直径.

Question

如题所述

Answer 1

是求半圆环的面积吧?
[ 3.14 × (10 ÷2) × (10 ÷ 2) - 3.14 × ( 6 ÷ 2) × (6 ÷ 2) ] ÷ 2
= (3.14 × 5 × 5 - 3.14 × 3× 3) ÷ 2
= 3.14 × ( 25 - 9) ÷ 2
= 3.14 × 16 ÷ 2
= 25.12