第2个回答 2014-01-28
(1)S 阴影=S大1/4圆-S小1/2圆
2 2
=3.14x8 除以4-3.14x(8除以2)除以2
=3.14x(64除以4)-3.14x(16除以2)
=3.14x16-3.14x3.14x8
=3.14x(16-8)
=3.14x8
=25.12(平方厘米)
(2)S 阴影=S小1/4圆
2
=3.14x4 除以4
=3.14x(16除以4)
=3.14x4
=12.56(平方厘米)
(3)① 2 ②(8+6)x6除以2-7.74
6x6-3.14x6 除以4 =14x(6除以2)-7.74
=36-3.14x(36除以4) =14x3-7.74
=36-3.14x9 =42-7.74
=36-28.26 =34.26(平方厘米)
=7.74(平方厘米)
(4)S阴影=S环形 2 2
=3.14x【8 -(8-3)】
=3.14x【64-25】
=3.14x39
=122.46(平方厘米)