题目内容
(本小题满分12分)
如图,
为圆
的直径,点
、
在圆
上,且
,矩形
所在的平面和圆
所在的平面互相垂直,且
,
.
(Ⅰ)求四棱锥
的体积
;(Ⅱ)求证:平面
平面
;
(Ⅲ)在线段
上是否存在一点
,使得
平面
,并说明理由.![](http://thumb.1010pic.com/pic2/upload/papers/20140823/201408231626444361877.gif)
如图,
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162643515228.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162643546203.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162643562197.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162643593196.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162643546203.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162643624403.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162643640389.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162643546203.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162643687275.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162643718493.gif)
(Ⅰ)求四棱锥
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162643734354.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162643936403.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162643952376.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644155252.gif)
(Ⅲ)在线段
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644170234.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644358327.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644404395.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644420273.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/201408231626444361877.gif)
(1)略
(2)取
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644451236.gif)
解:(Ⅰ)
-------------------------1分
作
交
于一点
,则
---2分
平面
平面![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644748406.gif)
面
---3分
所以
---4分
(Ⅱ)
平面
平面
,
,
平面
平面
=
,
平面
,
平面
,
,……… 6分
又
为圆
的直径,
,
平面
.……… 7分
面
,
平面
平面
;……… 8分
(Ⅲ)取
中点记作
,设
的中点为
,连接
,![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646214368.gif)
则![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646214368.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646339141.gif)
,又![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646417241.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646339141.gif)
,则![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646214368.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646339141.gif)
,
所以
为平行四边形, ……… 10分
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646557404.gif)
,又
平面
,
平面
,
平面
.……… 12分
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644482673.gif)
作
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644529419.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644545234.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644576213.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644592711.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644607133.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644732327.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644748406.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644763271.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644779301.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/201408231626449662007.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/201408231626449821132.gif)
(Ⅱ)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644607133.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644732327.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644748406.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162645060318.gif)
平面
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162645138359.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644748406.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162645169235.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162645340270.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644748406.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162645528268.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644748406.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162645559334.gif)
又
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162645590254.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162645777209.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162645808326.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162645840259.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162645855272.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162645871270.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162645886261.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162645902128.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162643952376.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644155252.gif)
(Ⅲ)取
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162644451236.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162645980327.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646011241.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646167211.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646183241.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646214368.gif)
则
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646214368.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646339141.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646386323.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646417241.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646339141.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646386323.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646214368.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646339141.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646417241.gif)
所以
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646542440.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646557404.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646573236.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646588365.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646604278.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646620404.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646604278.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646557404.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823162646604278.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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