如图,在直三棱柱
中,
.
(1)证明:
为直角三角形.
(2)若
为等腰三角形,且
,求
与侧面
所成角的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f55171d348ce35d913d70b7fddacf168.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/6/21/ca2bee8d-65d8-4c8f-8b1c-d99832fb09cc.png?resizew=130)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c268ff5785e303b8420de92b2ef680c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24bb49fdc6b6bbb2449fdf8a0de769d3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab3e0dba5705e1d749cfb21ebbb2ed93.png)
更新时间:2023-06-18 18:09:16
|
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解答题-证明题
|
适中
(0.65)
解题方法
【推荐1】如图,平行四边形ABCD中,
,线段
的垂直平分线为AE,垂足为
,将
沿AE翻折到
,此时点
在平面
上的射影恰为点E.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/19/2d443b60-28c5-4eef-8b44-39bb0071b4e1.png?resizew=310)
(1)若
,求证:平面
平面
;
(2)若直线
与平面
所成的角小于
,求AE的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcd0ced286a0fbc7e4862f8147264277.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63b43490ca09467a4c8cd8cfe91c94e4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0374b8c5e00f831181538ba2f3675c1f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7c314398e26ffc7164b82946eeb4273.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01ff27eea7545bb06f9472f91290c54e.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/19/2d443b60-28c5-4eef-8b44-39bb0071b4e1.png?resizew=310)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b348d598a0fc163951e1145909910d43.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/da23c83e765a1bd5705800a7d80619ee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1bb31d531a1988bcf23e2d81a80f9048.png)
(2)若直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6eb97aff0960e2640314888a38e7169c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9db7e46fef4f27799aec83a8bfb8eae8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3598b267a362446bdec58695f55575fd.png)
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解答题-证明题
|
适中
(0.65)
解题方法
【推荐2】四棱柱
中,
平面
,
为梯形,
,
.
(1)求证:
平面![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab3e0dba5705e1d749cfb21ebbb2ed93.png)
(2)
为平面
上一动点,是否存在
使得
与平面
的夹角为
,若存在,求出
到平面
的最小值,若不存在,说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5845ccc0d735dc14c92a8926d9b1def6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce519312a849963b376c202c3f9d7cf7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6155f82a6f64b20085976cea9b64193.png)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a5928c98b341b16d4b5a5b931d2929d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab3e0dba5705e1d749cfb21ebbb2ed93.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15dc61d5de97b5a40be925b278ae494c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e86eec8526479272d15bb3b171a46de0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eb085eeb69401f4e1fa0e69f893cbd18.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e86eec8526479272d15bb3b171a46de0.png)
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解答题-证明题
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【推荐1】已知四棱锥
的底面ABCD是菱形,
,AD的中点M是顶点P在底面ABCD的射影,N是PC的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/7/6fb16e51-efc4-44cc-aa4a-44886626a061.png?resizew=190)
(1)求证:平面
平面PBC;
(2)若
,求直线BN与平面PMC所成角的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f7dbf31dfd36aa456a63bafea8bc1985.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/7/6fb16e51-efc4-44cc-aa4a-44886626a061.png?resizew=190)
(1)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/47371dc84ad8517cac39856065235395.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b723672c82c0affb2e2e1ac5c00a2cc9.png)
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解答题-证明题
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名校
【推荐2】如图,几何体ABCDEF中,
,
均为边长为2的正三角形,且平面
平面DFE,四边形BCED为正方形,平面
平面ABC.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/30/24caa41c-fac3-4349-84cf-e2c6fe74b77b.png?resizew=179)
(1)求证:平面
平面BCF;
(2)求直线AD与平面BCED所成角的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a3fd09f591e95fd40e8ecfe6020f9f46.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/617edf7f259f5955db7cad814af85281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce800ada0934832b028ccebb2a81637d.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/30/24caa41c-fac3-4349-84cf-e2c6fe74b77b.png?resizew=179)
(1)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d782bc4aad7cf35baa3de7b8ea73e41f.png)
(2)求直线AD与平面BCED所成角的正弦值.
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