如图,已知长方体
中,
,点E是
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/19/3e427fbb-8821-419b-8a55-be0736d6b9aa.png?resizew=205)
(1)求证:
平面
;
(2)求点E到平面
的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9662bb2fa5e9f9a2958c5c628f5a51b0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/554b3b4c5ce7aca81becc07ed4903736.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/19/3e427fbb-8821-419b-8a55-be0736d6b9aa.png?resizew=205)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3b7bfc1d0b50681765bd3fa6d5920ed8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/65277734669566578cbb7d690bb200fb.png)
(2)求点E到平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cc78a86b12ba0b4553135a3a635fc418.png)
更新时间:2022-05-29 10:04:41
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【推荐1】(1)给出两块相同的正三角形纸片(如图1、图2),要求用其中一块剪拼成一个正三棱锥模型,另一块剪拼成一个正三棱柱模型,使它们的全面积都与原三角形的面积相等.请设计一种剪拼方法,分别用虚线标示在图1、图2中,并作简要说明.
(2)试比较你剪拼的正三棱锥与正三棱柱的体积的大小.
(3)如果给出的是一块任意三角形的纸片(如图3),要求剪拼成一个直三棱柱模型,使它的全面积与给出的三角形的面积相等呢?
(2)试比较你剪拼的正三棱锥与正三棱柱的体积的大小.
(3)如果给出的是一块任意三角形的纸片(如图3),要求剪拼成一个直三棱柱模型,使它的全面积与给出的三角形的面积相等呢?
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【推荐2】如图,在正四棱柱
中,
,
,M为棱
的中点
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/27/a9888988-b90e-4111-945b-4dadfff6b41b.png?resizew=125)
(1)求三棱锥
的体积;
(2)求直线
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/fcd0ced286a0fbc7e4862f8147264277.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8d8cb98c0adee7ca698d8b17dacb845b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0a851907ada2ac2c3c4880a6736d28a.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/27/a9888988-b90e-4111-945b-4dadfff6b41b.png?resizew=125)
(1)求三棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/283f3b88373640e012bbcd78931d1065.png)
(2)求直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5563473602e1b17d582a165b7b7b6b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/632f2bf1cd0435041fa04b01901d1c8c.png)
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【推荐1】如图,已知四棱锥
,底面
为菱形,
平面
,
,
是
的中点.
(1)判定
与
是否垂直,并说明理由.
(2)设
,若
为
上的动点,若
面积的最小值为
,求四棱锥
的体积.
![](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/051f092cbf89536d7e8b9fbf9d49355d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
(1)判定
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0629ce42392a7fe9be21d25c39c3e64.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcd0ced286a0fbc7e4862f8147264277.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73465a1f9aa03481295bf6bd3c6903ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0629ce42392a7fe9be21d25c39c3e64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d43af5a1c59dfeb9819827b19f72db1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/839c7616cd0d90265f4b2c9c021254fe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://img.xkw.com/dksih/QBM/2011/6/2/1570231039647744/1570231045152768/STEM/0a477458e86b4c2297d2c39ba6a00adb.png?resizew=203)
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解题方法
【推荐2】矩形ATCD中,
,
,B为TC的中点,
沿AB翻折,使得点T到达点P的位置.连结PD,得到如图所示的四棱锥
,M为PD的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/9/17efd663-65fe-49b2-b3bb-aa48d577778f.png?resizew=361)
(1)求线段CM的长度;
(2)若平面
平面ABCD,求三棱锥
的体积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04ee826937d2add7a93aaa1422f8b736.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/40560ea08d6cd8c1d4d9661ee6faaa3b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a04e30d5827f2120d997997e4e31ba17.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/9/17efd663-65fe-49b2-b3bb-aa48d577778f.png?resizew=361)
(1)求线段CM的长度;
(2)若平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93edc7bb513f40a89173121c8570cd65.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ddfe0ccf24d760c77535a70c92dad145.png)
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【推荐1】如图所示,四棱锥
的底面是矩形,PA⊥平面ABCD,E、F分别是AB、PD的中点,
.
![](https://img.xkw.com/dksih/QBM/2018/10/22/2059175405600768/2059241775833088/STEM/620c282cccbd4e59a84c5cbe5dec35fe.png?resizew=168)
(1)求证:AF∥平面PEC;
(2)求证:平面PEC⊥平面PCD;
(3)设AD=2,CD=2
,求点A到平面PEC的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fb6823ce3888cb560cfa4984dc2f307.png)
![](https://img.xkw.com/dksih/QBM/2018/10/22/2059175405600768/2059241775833088/STEM/620c282cccbd4e59a84c5cbe5dec35fe.png?resizew=168)
(1)求证:AF∥平面PEC;
(2)求证:平面PEC⊥平面PCD;
(3)设AD=2,CD=2
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf298f00799cbf34b4db26f5f63af92f.png)
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【推荐2】如图,在四面体
中,
面
,
是
的中点,
是
的中点,点
在线段
上,
且
.
,求证:
平面
.
(2)若二面角
为
,求二面角
的余弦值.
(3)若三棱锥
的体积为1,求三棱锥
外接球的体积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/891579e7c231584a8e16b8eeff79888e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca5dd496ee0c1170ef6dcc48266ee444.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca67a5b8f69507c8b80379e86f90a8ce.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e69d2b798744645af88a4fa411344a83.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4bd6a2b112facda441f4e34bf5c145fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08ad8d16722f5b9e7fd2602f14d5ffbe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/276e3c9755dbd39fb01de614840d230f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/72221ee5b504d596ff799c0b356aa0ea.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca67a5b8f69507c8b80379e86f90a8ce.png)
(2)若二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ec2524be492bca0d1566bf848066f10.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1e5fa72f2878b476bc57f0df12d6555.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d6eed8e6e9bea8c21b2688268f4fb7e6.png)
(3)若三棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81b1b8ad73dd13cb734206cfe15ada5e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/891579e7c231584a8e16b8eeff79888e.png)
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【推荐1】如图,四边形
为正方形,
平面
,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/20/708d3b87-ec3b-4fb7-904b-b3a108816b70.png?resizew=240)
(Ⅰ)求证:
;
(Ⅱ)求点
到平面
的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a1b49f64e0065edad868b25e9fcada3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/133659fd88416259e3b99eaf5751b98d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1b051c27cb61a31085d953a53f766541.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/20/708d3b87-ec3b-4fb7-904b-b3a108816b70.png?resizew=240)
(Ⅰ)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ecf6c62979a7aa534a191d8387a741e8.png)
(Ⅱ)求点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4afa84f553561b598228240957f0c51e.png)
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【推荐2】在直三棱柱
中,
,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/15/005517d6-6053-44dd-8810-83bb91ce2349.png?resizew=172)
(1)求异面直线
与
所成角的大小;
(2)求点
与平面
的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/45acdbac251ca6b76a166c1242e71df9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/829018a6ca0aff95d89e3f7cd943274e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/41fd676c41d2d644928f014b0fea4689.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/15/005517d6-6053-44dd-8810-83bb91ce2349.png?resizew=172)
(1)求异面直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56f7ba05c54b3de1f4378f7c8eb58328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3ee8456443402a25b1e25d35ff7e1c98.png)
(2)求点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97c01fdc7bc471af0b264a04aef0823e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9afac7c616bbb14e1ed428a3c507c7dc.png)
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【推荐3】已知四棱锥P-ABCD中,PA⊥底面ABCD,AD∥BC,AB=AD=3,BC=4,AC=5.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/2/27600876-9127-45c9-b404-b9fa3c42d46e.png?resizew=172)
(1)当AP变化时,点C到平面PAB的距离是否为定值?若是,请求出该定值;若不是,请说明理由;
(2)当直线PB与平面ABCD所成的角为
时,求二面角A-PD-C的余弦值.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/2/27600876-9127-45c9-b404-b9fa3c42d46e.png?resizew=172)
(1)当AP变化时,点C到平面PAB的距离是否为定值?若是,请求出该定值;若不是,请说明理由;
(2)当直线PB与平面ABCD所成的角为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1e5fa72f2878b476bc57f0df12d6555.png)
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