在如图所示的几何体中,四边形
是等腰梯形,
,
,
平面
,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/10/a6834865-7d31-48c9-ae2e-205ec37a38b5.png?resizew=176)
(1)求证:
平面
;
(2)求直线
与平面
所成角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/10df84d553a8826a7ce9bff4bf0d95b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea4f5eec0addba78f2e0cdfb7ecc59a6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b7b5a90e556da12d63b7f481bd8e874c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/53c51c25b65a37b676ae3c3b71c29f9b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f5e3c3447ba182c0bbf051b21132dd4f.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/10/a6834865-7d31-48c9-ae2e-205ec37a38b5.png?resizew=176)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/111da2c687a67fd089c365090908eb00.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97a9b32570d553161be04d13954e92a1.png)
(2)求直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6aa2b5e09f8ec785c59900a529390a02.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ae8768996ca9a0f2c5d9a19abbd54df.png)
更新时间:2018-01-19 14:16:04
|
相似题推荐
解答题-证明题
|
适中
(0.65)
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解题方法
【推荐1】中国古代数学名著《九章算术》中记载:“刍甍者,下有表有广,而上有表无广刍,草也,甍,屋盖也”.翻译为“底面有长有宽为矩形,顶部有长没有宽为一条棱;刍甍为茅草屋顶”,现将一个正方形折叠成一个“刍甍”,如图1,E、F、G分别是正方形的三边AB,CD,AD的中点,先沿着虚线段FG将等腰直角三角形FDG裁掉,再将剩下的五边形ABCFG沿着线段EF折起,连接AB,CG就得到了一个“刍甍”,如图2.
平面GCF;
(2)若二面角A—EF—B的大小为
,求直线AB与平面GCF所成角的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8918734c91aba3280ca73a44edd28370.png)
(2)若二面角A—EF—B的大小为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/732250efe9c8c0cbca127fb2ed2a4bf9.png)
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【推荐2】如图所示,在三棱柱
中,点D是AB的中点.
![](https://img.xkw.com/dksih/QBM/2021/12/24/2879473189847040/2879712556728320/STEM/56dc7149-9034-4c5a-8e69-a8f058538f29.png?resizew=198)
(1)求证:
平面
.
(2)若
平面ABC,
,
,
,求二面角
的平面角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://img.xkw.com/dksih/QBM/2021/12/24/2879473189847040/2879712556728320/STEM/56dc7149-9034-4c5a-8e69-a8f058538f29.png?resizew=198)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/89006cac018a9875f65ed7bd429c61bf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cbc7e774e4ae40c23bf4ceed179230ca.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5845ccc0d735dc14c92a8926d9b1def6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/615fc8790237a1b09af51d6bcad6b595.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad1a56baf43ffdf67bc8460856e31fec.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19bc7774144c164f7ebaeca54fa657e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fdfbed46cc4e02768687c8ba14b7d2c6.png)
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【推荐3】如图,在四棱锥
中,底面
为直角梯形,
,
,点
是
中点.
(1)证明:
平面
;
(2)若面
面
,求二面角
的余弦值.
![](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/db58b697e8fbe5219813746f3ee4c4b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b06081399c6ca4112e7172896fcaec04.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/3/4b7112ff-8990-472d-9300-214a83932a2f.png?resizew=183)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f369bec2d5682bf6b8b317a08aff546.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/852aabd89edffc1b94344ff3f1f31ccd.png)
(2)若面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93edc7bb513f40a89173121c8570cd65.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5451ce8cf47f48632e665df940968c8.png)
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【推荐1】已知正方体
的棱长为2,设
分别为棱
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/23/31b91dd2-9986-4000-b971-424aa8bc6603.png?resizew=166)
(1)证明:
//平面
;
(2)求BQ与面BDP所成角的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6bce3d91ca23b86d8c6625f2632e437.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b596acf1d7d59eac629a7831547f544.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/23/31b91dd2-9986-4000-b971-424aa8bc6603.png?resizew=166)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/84d454c82d9e52747563d47b68099249.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8f571a1aac46c6d0cf440c0ec2846bf9.png)
(2)求BQ与面BDP所成角的正弦值.
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解题方法
【推荐2】在正四棱柱
中,
,E为
的中点,F为
上靠近B的三等分点.
所成角的余弦值;
(2)求直线CF与平面
所成角的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2f21c7c194c5bc2986a21fd441c81495.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/22adbc0da438220f9cace11b629d799b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fe734023d4e70010a6b2cc3267cb86e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e516121599c9fcc528121c00afcf52fc.png)
(2)求直线CF与平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/45d365ce9f4bacc4d4bb15dbdb5306a5.png)
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解答题-问答题
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【推荐3】如图,在矩形
中,
,
为边
的中点,以
为折痕把
折起,使点
到达点
的位置,且使平面
平面
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/3/b50f0bba-9bdc-4521-8909-5c3c76d3aa21.png?resizew=222)
(1)证明:
;
(2)求直线
与平面
所成角的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f80f51c31583fea58fde645474d60b8a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccaee8f228ff24e7c89879bb5b999cf2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/55c3c8bf858c13b295de56e548116db9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2c505f9d4513028bb16e274aae96cba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e1d70676406f26d339465fe3473c0c05.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/3/b50f0bba-9bdc-4521-8909-5c3c76d3aa21.png?resizew=222)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6aaef9e92d148afff22761d5e027d3ee.png)
(2)求直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e582d73b96ba649378379c3074d506d.png)
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