如图所示的四棱锥P—ABCD中,底面ABCD为菱形,PA⊥平面ABCD,E为PC的中点,求证:
![](https://img.xkw.com/dksih/QBM/2015/7/2/1572160975085568/1572160980369408/STEM/cf72be4fd9a14744b1a339598cf9baa0.png?resizew=168)
(1)PA∥平面BDE;
(2)平面PAC⊥平面PBD.
![](https://img.xkw.com/dksih/QBM/2015/7/2/1572160975085568/1572160980369408/STEM/cf72be4fd9a14744b1a339598cf9baa0.png?resizew=168)
(1)PA∥平面BDE;
(2)平面PAC⊥平面PBD.
更新时间:2016-12-03 15:12:36
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解答题-问答题
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解题方法
【推荐1】如图①,在等腰三角形
中,
,
,
,
满足
,
.将
沿直线
折起到
的位置,连接
,
,得到如图②所示的四棱锥
,点
满足
.
![](https://img.xkw.com/dksih/QBM/2021/3/30/2688846566506496/2688914521669632/STEM/ea0b3fbe-90b7-45c7-bdaa-239cf87b17e2.png)
(Ⅰ)证明:
平面
;
(Ⅱ)当
时,求三棱锥
的体积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7b7c83470489253394bd288d7c920df.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/94911ca2a27e4a36c55cdd44a74a9a5d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/07160f14b3b453bebb64cb2bf96dc85a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61cf3bace2a2452486451f1b7327abe0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4d4d8263a27e302a146af84b3812c32e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7cff7399ecc698e2fb415147c96d0d03.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a25c28359f8d8da9eaf4672a6cf8ae4f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8e7cedc39297d66dbb177f2a1f6bee2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a85b9860b5da8e4a978da5f4dc356438.png)
![](https://img.xkw.com/dksih/QBM/2021/3/30/2688846566506496/2688914521669632/STEM/ea0b3fbe-90b7-45c7-bdaa-239cf87b17e2.png)
(Ⅰ)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4a2b5cfae407016cad45bbdefea05833.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c66d99a6a8415ddad22bbed33b64cfb.png)
(Ⅱ)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bb88289c2aed70bade0bddea6d1dd72b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8511319e215aeba124994a03f2d91fcb.png)
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解答题-证明题
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名校
【推荐2】如图所示,
是正三角形,线段
和
都垂直于平面
,设
,
,且
为
的中点.
![](https://img.xkw.com/dksih/QBM/2019/9/23/2296989600948224/2297077380653056/STEM/26ac1047-87c6-41f2-ab50-0a4732c6f38b.png)
(1)求证:
平面
;
(2)求平面
与平面
所成的较小二面角的大小
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1642eec556eb252de9c1ab7bb5ca90b3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e52a8f07834cbbbe4224962672fbbb2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fa3b1722b100297f2fa8fad62423149d.png)
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(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/101cb6a0840ab7269e90f2f019cd957b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
(2)求平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/34be4e71cabf458f17a6cd7f24bc70af.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
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【推荐3】如图,在棱长为2的正方体
中,E为
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/19/62654cb0-0cdb-4014-b490-60f3c3454266.png?resizew=156)
(1)求证:
平面
;
(2)求平面
与平面
夹角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0a851907ada2ac2c3c4880a6736d28a.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/19/62654cb0-0cdb-4014-b490-60f3c3454266.png?resizew=156)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f5830646a912c3a916beac4f88c116b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f2331bccb6ebf5b9fd639df994f575a9.png)
(2)求平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e168672b47d7e64dc1b404f8882c7dcf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f2331bccb6ebf5b9fd639df994f575a9.png)
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【推荐1】在四棱锥
中,四边形
是直角梯形,
,
,
底面
,
,
,
,
是
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/17/772fb74b-364b-4883-98cd-19851abfbcf1.png?resizew=167)
(1)求证:平面
平面
;
(2)
上是否存在点
,使得三棱锥
的体积是三棱锥
体积的
.若存在,请说明
点的位置;若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
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![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/17/772fb74b-364b-4883-98cd-19851abfbcf1.png?resizew=167)
(1)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/677d1863ff4d8ac1604b18149d4f320f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7b7c83470489253394bd288d7c920df.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0629ce42392a7fe9be21d25c39c3e64.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
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【推荐2】如图1,菱形
的边长为
,
,
与
交于点
,将菱形
沿对角线
折起,得到三棱锥
,点
是棱
的中点,
;
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/4/c6ab1afa-865b-4ab9-b702-280a6fdaced1.png?resizew=285)
(1)求证:平面
平面
;
(2)求点
到平面
的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f8c4c029e552954bd493b49aeab82d5.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36552f4ac365373c91949981301a8d8e.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/4/c6ab1afa-865b-4ab9-b702-280a6fdaced1.png?resizew=285)
(1)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/50c6ba492928fba5b5f06ed648c4c621.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
(2)求点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7abd284f76d9f5769bc189508ce2572b.png)
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