名校
解题方法
1 . 如图,在长方体
中,点
、
分别在棱
,
上,且
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/28/7f429009-e7ae-4839-899c-c5ca5034a9a6.png?resizew=130)
(1)求证:
,
,
,
四点共面;
(2)若
,
,
,求平面
与平面
夹角的正弦值;
(3)在(2)的条件下,求点
到平面
的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2777840758e70e7dbbc18cef8f3d6d2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d88bf46ad08f9677c37eed1d0369329.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/18f166fe0e3f4196b7a34c5ed309a597.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2ce1f746c5da3cb8280f3a0b724a113f.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/28/7f429009-e7ae-4839-899c-c5ca5034a9a6.png?resizew=130)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6795cae2df43a722e1355e9562d93c09.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcd0ced286a0fbc7e4862f8147264277.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09d27bd71d79cb19eb554175e4ef0867.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e8d927585a17c2e98ef7d5a9589a26ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/134ef0b1a2669a09f05bd4dc2496f706.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ae8768996ca9a0f2c5d9a19abbd54df.png)
(3)在(2)的条件下,求点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/134ef0b1a2669a09f05bd4dc2496f706.png)
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2 . 在正方体
中,
平面
,若
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e5085e3cdef9ea6c564e079f745d6fdb.png)
_______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f904c1eed0804b9347c206ea167f1aa9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1507d849b729c520eaaf16657368e30b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/22efcc118ef52069c1485670ccd26687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e5085e3cdef9ea6c564e079f745d6fdb.png)
您最近一年使用:0次
3 . 如图,在边长为2的正方形ABCD中,E,F分别为BC,CD的中点.以DE为折痕将四边形ABED折起,使A,B分别到达
,
,且平面
平面CDE.设P为线段CE上一点,且
,
,P,F四点共面.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/2/f88c4000-c471-45dd-8fff-d63b1ee524de.png?resizew=180)
(1)证明:
平面
;
(2)求CP的长;
(3)求平面
与平面CDE所成角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a18722354086c42e62334983fc50eb6a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97c01fdc7bc471af0b264a04aef0823e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc64c3c72ee23f883844c546258baf83.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a18722354086c42e62334983fc50eb6a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97c01fdc7bc471af0b264a04aef0823e.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/2/f88c4000-c471-45dd-8fff-d63b1ee524de.png?resizew=180)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a5ee7171f282b6aaafa03fd22313e8f2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9857316a93ee2289a32a3ef3c589e9b3.png)
(2)求CP的长;
(3)求平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3357f6f7f7bd5f63662adf194f0706fb.png)
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