如图,在底面是正三角形的三棱锥
中,D 为PC的中点,
,![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d88c451a2739220040aef5e1955137ea.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/3/37e50df1-0db3-40b4-b648-e6f2f35338bb.png?resizew=131)
(1)求证:
平面
;
(2)求 BD 与平面 ABC 所成角的大小;
(3)求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc2aaed1e9ead175f30f7130569d0411.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/011bb74e4f70eb7739fdd1e9b2d0567b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d88c451a2739220040aef5e1955137ea.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/3/37e50df1-0db3-40b4-b648-e6f2f35338bb.png?resizew=131)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb4564baf209de77802d46cda82995c5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/787ac5e13622afab5e9f8603afe42356.png)
(2)求 BD 与平面 ABC 所成角的大小;
(3)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f593e4bb5b9b996b7d745c1ccfb78ac.png)
更新时间:2019-01-29 21:00:42
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解答题-证明题
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【推荐1】如图,已知多面体ABCDEF中,
平面ABCD,
平面ABCD,且B,D,E,F四点共面,ABCD是边长为2的菱形,
,
.
![](https://img.xkw.com/dksih/QBM/2022/5/6/2973798703079424/2974844274810880/STEM/b3bcbd3618584b4f81f008440c618d4b.png?resizew=197)
(1)求证:
平面ACF;
(2)求平面AEF与平面BCF所成锐二面角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7a38e6c6dfde2b19b6b47f35a439a06.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/06222ee533c2484ab25321a6abbf98cb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f945a69cf7e8213e50622125cde652f5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/334fec9ec91596bf9d2b41568123715f.png)
![](https://img.xkw.com/dksih/QBM/2022/5/6/2973798703079424/2974844274810880/STEM/b3bcbd3618584b4f81f008440c618d4b.png?resizew=197)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4a5f445af1ae136773cb338920552ff2.png)
(2)求平面AEF与平面BCF所成锐二面角的余弦值.
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【推荐2】如图,在四棱锥P-ABCD中,底面ABCD是菱形,∠ABC=60°,
为正三角形,且侧面PAB⊥底面ABCD. E,M分别为线段AB,PD的中点.
![](https://img.xkw.com/dksih/QBM/2018/1/23/1866506492198912/1866742001876992/STEM/68e455cb-9aab-464b-b679-188185dcf87a.png?resizew=279)
(I)求证:PE⊥平面ABCD;
(II)求证:PB//平面ACM;
(III)在棱CD上是否存在点G,使平面GAM⊥平面ABCD,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/53502463cc76201000e02df314e58769.png)
![](https://img.xkw.com/dksih/QBM/2018/1/23/1866506492198912/1866742001876992/STEM/68e455cb-9aab-464b-b679-188185dcf87a.png?resizew=279)
(I)求证:PE⊥平面ABCD;
(II)求证:PB//平面ACM;
(III)在棱CD上是否存在点G,使平面GAM⊥平面ABCD,请说明理由.
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【推荐1】如图,在三棱柱
中,
平面ABC,
,D是
的中点.
与平面ABC夹角的余弦值;
(2)在直线CD上是否存在一点P,使得BP与平面
所成角的正弦值为
,若存在,求出CP的长;若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a8bfe2553e852df73185d017c0a62fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/883e5fdc1f720e16a6e79eaaeb683188.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d88bf46ad08f9677c37eed1d0369329.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7935fe3125f247b7bea4f065ce9ad985.png)
(2)在直线CD上是否存在一点P,使得BP与平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7935fe3125f247b7bea4f065ce9ad985.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/69a8b76e36783a69d14ec54af82c7df0.png)
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【推荐2】如图,在四棱柱
中,
平面ABCD,底面ABCD是矩形,
,
,
,M为
的中点.
![](https://img.xkw.com/dksih/QBM/2020/5/27/2471778311413760/2472423995228160/STEM/3ee1cb4d-f1aa-40b3-a36d-8b7259d33c8e.png)
(1)求证:D1M//平面BDC1;
(2)若棱
上存在点Q,满足
与平面
所成角的正弦值为
,求异面直线
与BQ所成角的余弦值.
![](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/ced06b71073e1bb777f326f06016ce17.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8f144992e1cbee34868abce1e5ad38c9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/462b1c65b1b233ab98a90c164c0968c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e26d9636ad77369535852c6e4493446a.png)
![](https://img.xkw.com/dksih/QBM/2020/5/27/2471778311413760/2472423995228160/STEM/3ee1cb4d-f1aa-40b3-a36d-8b7259d33c8e.png)
(1)求证:D1M//平面BDC1;
(2)若棱
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d88bf46ad08f9677c37eed1d0369329.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/16d41164f8a9f6fe32a9364f18f168dd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/53cdc56590b42b154608b4cf19462fa0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64f1145c162038df3c7184d9201c628e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5563473602e1b17d582a165b7b7b6b2.png)
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【推荐3】如图1,在菱形
中,
为
的中点,
.现将
沿
翻折至
,并连接
,得到如图2所示的四棱锥
,且
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/5/2654c016-6463-4aa1-8973-78439850393b.png?resizew=307)
(1)证明:
;
(2)在棱
上是否存在点
,使得
与平面
所成的角的正弦值为
若存在,求出
的值;若不存在,请说明理由.
![](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/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/526d4a676568360252d96d5ce0c3454a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a25c28359f8d8da9eaf4672a6cf8ae4f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4336efb6d0689ddad55295e336340d3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/589c3cc1f331dbb2248b0829039df7f3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4e98920101c174b991d7a8481707ab88.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d3ff0680cd736c1d1791dd94429af88c.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/5/2654c016-6463-4aa1-8973-78439850393b.png?resizew=307)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9829fc6685b59fdc609f32f30ebd9e6d.png)
(2)在棱
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63a253c7fdf589ee3dece13d5b5b5732.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15a424b50eaeafa6f302ffd95476cb86.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8f571a1aac46c6d0cf440c0ec2846bf9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8549d17620cd96ba90b38f7b34b67a1c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d25f48d2e4aca820cdc0fa468b7930d0.png)
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【推荐1】如图,在五面体
中,
,
,
,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/23/ab6dface-e78d-4500-99be-8e590e4cbb04.png?resizew=132)
(1)证明:
平面
;
(2)若
,
,求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9165d9bfbb0f0d19eb482c2a4c1b29b7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/10de2459bc376f9a3de90f74cc18ca7a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/080db3af81b29ed10144a1c2e2a4fb8a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5062332dbc3b2a7affd3f2da406ee777.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a2ea447f925f331ef2873252f905d97d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/51a63e890d326a8f7c3f13fb3ccf2761.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/23/ab6dface-e78d-4500-99be-8e590e4cbb04.png?resizew=132)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4a5f445af1ae136773cb338920552ff2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/500df0e782bb081e608f4bc1d576afcf.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/07140f277a35733d8c97577ccdd4e3ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4d163ba9cef35eb600387bcfbbda89ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0730e73ddbbf9184df15d3b1467e55e7.png)
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解答题-证明题
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适中
(0.65)
名校
解题方法
【推荐2】如图,在四棱锥C-ABEF中,平面ABEF⊥平面ABC,△ABC是边长为2的等边三角形,AB∥EF,∠ABE=90°,BE=EF=1,点M为BC的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/8/cd7dc69c-89ac-4300-9653-75d5e0da6fba.png?resizew=146)
(1)求证:EM∥平面ACF;
(2)求证:AM⊥CE;
(3)求二面角E-BC-F的余弦值.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/8/cd7dc69c-89ac-4300-9653-75d5e0da6fba.png?resizew=146)
(1)求证:EM∥平面ACF;
(2)求证:AM⊥CE;
(3)求二面角E-BC-F的余弦值.
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解答题-证明题
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适中
(0.65)
【推荐3】如图,在三棱柱
中,平面
平面
,
.
,
为
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/23/5f010224-ecaa-4f86-af86-54f4b4c79dd7.png?resizew=187)
(1)求证:
平面
;
(2)求证:直线
与
不垂直;
(3)求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61cdaadeae37736a1e6dd93fa1fe712f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab3e0dba5705e1d749cfb21ebbb2ed93.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/44ae6e1fdf5a4675c439b0d4e0362725.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b33ad89b19e4e089c0d03cd6efae9ed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2777840758e70e7dbbc18cef8f3d6d2b.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/23/5f010224-ecaa-4f86-af86-54f4b4c79dd7.png?resizew=187)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f6d39135a2f8472d66ea00eda3b13ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab3e0dba5705e1d749cfb21ebbb2ed93.png)
(2)求证:直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f1f229274a6e17977cc047814212589.png)
(3)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/174be5a45bdb0e8695350ee47e1293e4.png)
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