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标题: 求助啊,谁能回答这个问题 [打印本页]

作者: 懿囦 时间: 2012-10-3 20:52:20 标题: 求助啊,谁能回答这个问题

[attach]260151[/attach]

求助各位了.第二题怎么解答?在此谢谢了

作者: jeffnz 时间: 2012-10-3 21:33:07

关键部分被skykiwi的水印遮住了。。。

我就先去睡了。。

作者: ryantao2010 时间: 2012-10-3 21:39:37

目测是253级别的

作者: 懿囦 时间: 2012-10-3 22:19:03

jeffnz 发表于 2012-10-3 21:33
关键部分被skykiwi的水印遮住了。。。

我就先去睡了。。

the question is :find the volume obtained when the shaded region is rotated through 360 about the x-axis. firstly,Thank you for the reply.

作者: jeffnz 时间: 2012-10-4 15:51:17

懿囦发表于 2012-10-3 23:19
the question is :find the volume obtained when the shaded region is rotated through 360 about the ...

its easy.

Get the volume for the whole area under AB line.

The white bit can be obtained by calculating the area under that AB curve.

Then convert that white area into volume.

Subtract the whole volume with the white bit volume and its done!

作者: 懿囦 时间: 2012-10-4 20:05:41

jeffnz 发表于 2012-10-4 16:51
its easy.

Get the volume for the whole area under AB line.

thank you so much

作者: mml 时间: 2012-10-5 19:57:59

disk method吧好象叫。切成一片一片的，每片的面积是大圆-小圆，然后沿x axis做积分
从0到5
[attach]261572[/attach]

作者: mml 时间: 2012-10-5 19:59:08

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