具体解答如下
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/d6ca7bcb0a46f21f8e4a6f2ce6246b600c33ae56?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
将题目中坐标轴进行重新命名,就可以将题目转化为求上图红色区域与黑色区域绕y轴旋转所得图形体积。
红色区域绕y轴旋转
V=∫[π/2,π] 2πxsinxdx
=–2π∫[π/2,π] xdcosx
=–2πxcosx|[π/2,π] +2π∫[π/2,π] cosxdx
=2π²+ (2πsinx)|[π/2,π]
=2π²–2π
黒色区域绕y轴旋转
V=∫[0,π/2] 2πx(1–sinx)dx
=∫[0,π/2] 2πxdx+2π∫[0,π/2] xdcosx
=πx²|[0,π/2]+2πxcosx|[0,π/2]–2π∫[0,π/2] cosxdx
=π³/4–2π
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