如图所示的多面体ABCDEF满足:正方形ABCD与正三角形FBC所在的两个平面互相垂直,FB∥AE且FB=2EA.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/4/5a829407-5d6d-47eb-951a-8857602c4d46.png?resizew=167)
(1)证明:平面EFD⊥平面ABFE;
(2)求二面角E﹣FD﹣C的余弦值.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/4/5a829407-5d6d-47eb-951a-8857602c4d46.png?resizew=167)
(1)证明:平面EFD⊥平面ABFE;
(2)求二面角E﹣FD﹣C的余弦值.
更新时间:2020-03-15 20:05:38
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解答题-问答题
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适中
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名校
解题方法
【推荐1】如图,在三棱锥
中,
,二面角
为直二面角.
![](https://img.xkw.com/dksih/QBM/2022/4/15/2958566563348480/2965058287607808/STEM/ee2c03f8-9750-480c-80e8-7af895984049.png?resizew=143)
(1)若
,证明:平面ABD⊥平面ACD;
(2)若
,
,二面角
的余弦值为
.求CD的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/891579e7c231584a8e16b8eeff79888e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c06154cae3bf7a8ce5a1e97a7380875.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ec2524be492bca0d1566bf848066f10.png)
![](https://img.xkw.com/dksih/QBM/2022/4/15/2958566563348480/2965058287607808/STEM/ee2c03f8-9750-480c-80e8-7af895984049.png?resizew=143)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d3bbe4cdd2c154bd9a8073b0d4cecb8a.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bfd269940881dc236446cdff52cf3672.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e65a3e478bb87d094e3a0af30dd10ae8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd29cc627d76412c236aac6b29fa0fdf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4483fbccb86e51db927f5e7e08e0b044.png)
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解答题-证明题
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【推荐2】如图所示的空间几何体
中,四边形
是边长为2的正方形,
平面
,
,
,
,
.
![](https://img.xkw.com/dksih/QBM/2017/4/11/1663341618724864/1663558947717120/STEM/0c29e4864e3a4bb9b680c9cb753c2a95.png?resizew=191)
(1)求证:平面
平面
;
(2)求平面
与平面
所成的锐二面角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d20e38a1b5cfffd43a3405481a1d67cd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f4c3f9dd5d0343597a7f58a1989b537.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/058f36d315245b63a811d5c6f348c17b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cdc143c7fd7c471ca91b6ccc22438fdd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1c5602f77ca3a869d3898320643005a8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/86338536656046e93b53672ade9a78b3.png)
![](https://img.xkw.com/dksih/QBM/2017/4/11/1663341618724864/1663558947717120/STEM/0c29e4864e3a4bb9b680c9cb753c2a95.png?resizew=191)
(1)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09f5c2097f668c484d698d7f59c237ed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c66d99a6a8415ddad22bbed33b64cfb.png)
(2)求平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d666dd3308604685e59f4ca22663b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
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解答题-证明题
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解题方法
【推荐3】已知四棱锥
,其中
面
,
,
为
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/12/7e62add0-f334-438b-8e54-a239dfb8afdd.png?resizew=172)
(Ⅰ)求证:
面
;
(Ⅱ)求证:面
面
;
(Ⅲ)求四棱锥
的体积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5164a3cc47e266446d49127e2ef10c37.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/604268293c7bf67997f40a9a0b0d1cd9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e9e22143a3f0cb2de51f382836cc274e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/12/7e62add0-f334-438b-8e54-a239dfb8afdd.png?resizew=172)
(Ⅰ)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/57f9d682e5d3cc8573574d8d11636758.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
(Ⅱ)求证:面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4d28c625d7ac6878957facc8274d459c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4eb7e9ad5486cf1c5e506b20c5469e8.png)
(Ⅲ)求四棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5164a3cc47e266446d49127e2ef10c37.png)
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解答题-问答题
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【推荐1】如图,四棱锥
的底面
为矩形,
平面
,点
是棱
的中点,点
是
的中点.
(1)证明:
∥平面
;
(2)若底面
为正方形,
,求二面角
大小.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccd4fd4b7a4d6b8ca0c5827c055a9ce7.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/e0629ce42392a7fe9be21d25c39c3e64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/46e2da608b66c9aee03e2503388ba4fd.png)
(2)若底面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/74107ed86d62c4a2ca1630d626dff115.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/206695fadf6ab817ae8650f47fbf65d3.png)
![](https://img.xkw.com/dksih/QBM/2017/7/4/1722987557519360/1724844513492992/STEM/7b43a1d23c9a47468f4e1bce0d05c756.png?resizew=250)
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解题方法
【推荐2】如图所示,四棱锥
中,底面
为菱形,点
在底面的投影
点恰好是菱形
对角线交点,点
为侧棱
中点,若
,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/11/675ecb92-1a97-49d0-ab50-007ad800a1f4.png?resizew=186)
(1)求证:平面
⊥平面
;
(2)点
在线段
上,且
,求二面角
的平面角的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f945a69cf7e8213e50622125cde652f5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcd0ced286a0fbc7e4862f8147264277.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c8d245c35c56ded2ceb001c06a5d0ca7.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/11/675ecb92-1a97-49d0-ab50-007ad800a1f4.png?resizew=186)
(1)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7b7c83470489253394bd288d7c920df.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/34be4e71cabf458f17a6cd7f24bc70af.png)
(2)点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bd33764ff4efddfe11a98a609753715c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a862ec7c8b3dc2682988b28cbbb5d5aa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca64fb6cecb2747e650488fed5550f7d.png)
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