名校
解题方法
1 . “风筝”是中国传统文化中不可或缺的一部分,距今已有2000多年的历史.相传在东周春秋时期,墨翟以木头制成木鸟,是人类最早的风筝起源.后来鲁班用竹子,改进墨翟的风筝材质,直至东汉期间,蔡伦改进造纸术后,坊间才开始以纸做风筝,称为“纸鸢”.到南北朝时,风筝开始成为传递信息的工具;从隋唐开始,由于造纸业的发达,民间开始用纸来裱糊风筝;到了宋代的时候,放风筝成为人们喜爱的户外活动.风筝主要由骨架、风筝面、尾翼、提线、放飞线五部分组成.如图(1)就是一个由菱形的风筝面ABCD和两个直角三角形尾翼
和
所组成的风筝.其中
,
,
,
,
.现将此风筝的两个尾翼分别沿
折起,使得点P与点Q重合于点S,并连结
,得到如图(2)所示的四棱锥
.
平面
;
(2)若E为棱
上一点,记![](https://staticzujuan.xkw.com/quesimg/Upload/formula/968088978992ba767468dec2dc436350.png)
①若
求直线
与平面
所成角的正切值;
②是否存在点E使得直线
与直线
所成角为
,若存在请求出
的值,若不存在请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d41984f53bb280ba8b5ac00a52ce2825.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d96645a3530e72d5d733d2c72147d340.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bb8fb552b9e21dbaba74d11aa747790.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/37002ada5d194d4d062fa3285d7d9824.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d899b31ac8800258c52e86a70e7ab9ed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f4aca5534bce25acaeb7379deed8f8f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/12a0f2f623bbe6beb1fdbc767bc1ba70.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4a887678ca42faa3d289e2b6460790b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7b5e290c6b2c5508a3bf6117afbf7e1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/faeb97acf19bd3b2c6c77c2814df4d2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e56fdf217165748fafe938b64fa08179.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5000fea066102e62cf2128ccbbd2b3e3.png)
(2)若E为棱
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a6e2867f32d3f1c3cd36cd3a11a8580.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/968088978992ba767468dec2dc436350.png)
①若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac1c3ea872a20fdc1843cb5ffce8a554.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5000fea066102e62cf2128ccbbd2b3e3.png)
②是否存在点E使得直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be6a6301878fed2a01413020b27310a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df64046e91b047037f19e4032e3b6de3.png)
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