1 . 如图(1),边长为
的正方形
中,
,
分别为
、
上的点,且
,现沿
把
剪切、拼接成如图(2)的图形,再将
,
,
沿
,
,
折起,使
、
、
三点重合于点
,如图(3).
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/22/6036a81c-da8b-48be-9c6e-687c673771bf.png?resizew=378)
(1)求证:
;
(2)求二面角
最小时的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2dde327febef2331a4766a79b433cc02.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6aa2b5e09f8ec785c59900a529390a02.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3a0a24ab1d027cb14725a6a758a6c785.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e52a8f07834cbbbe4224962672fbbb2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8414369aceaa4231d66c698380926b14.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b1a2dbe2665ec6a0fadff8e19da12f9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8414369aceaa4231d66c698380926b14.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db5e1441a49e782ff0ef46e776cde06a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7c314398e26ffc7164b82946eeb4273.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/22/6036a81c-da8b-48be-9c6e-687c673771bf.png?resizew=378)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73eb93407a3b472affa1748a1db672e2.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2fe90997c0a36e47450b5cbaea013781.png)
您最近一年使用:0次
2020-01-11更新
|
472次组卷
|
3卷引用:山东省德州市2019-2020学年高三上学期期末数学试题
山东省德州市2019-2020学年高三上学期期末数学试题(已下线)专题24 盘点立体几何中折叠问题——备战2022年高考数学二轮复习常考点专题突破江苏省连云港市灌南高级中学2022-2023学年高二下学期第一次月考数学试题
名校
2 . 如图,在三棱锥
中,平面
平面
,
和
均是等腰直角三角形,
,
,
、
分别为
、
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/5/88107e3f-fe40-4291-9413-ea576d7ceb4e.png?resizew=153)
(Ⅰ)求证:
平面
;
(Ⅱ)求证:
;
(Ⅲ)求直线
与平面
所成角的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c6a94d59dee2d5a8f0425b64b2083825.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11477bf45c2ad9d554d8f2dbacb5bb67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6677a7d5693deb7e41ed70ecca68f7de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3570a95f68349fcd9417fcda62e78e7e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2513bfc5f4c4cbc7c07725b9d59bda6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd4fce8e923062b9779553d6f282895b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95226c64f0afdaa10b95ec097a0720ea.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/5/88107e3f-fe40-4291-9413-ea576d7ceb4e.png?resizew=153)
(Ⅰ)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68fdb2b9d6a4a54ed1328c5b3adcf7b6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/70db40c42655327adee01caedfc9d50c.png)
(Ⅱ)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/99116c812715c5e15ee73d088da4c253.png)
(Ⅲ)求直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95226c64f0afdaa10b95ec097a0720ea.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/70db40c42655327adee01caedfc9d50c.png)
您最近一年使用:0次
2020-01-10更新
|
1034次组卷
|
6卷引用:北京市海淀区2019-2020学年高三上学期期末数学试题
2020高三·浙江·专题练习
3 . 如图,在三棱锥
中,
为等边三角形,
,
,
,
,
为
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/29/0e4b05c1-9b0b-467b-ae26-0df311c9c19c.png?resizew=175)
(1)求证:
;
(2)求直线
与平面
所成角的大小.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/41e5db1d2fd912f77923e4c120a7dc19.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a21c3a3e71fbec8a46dc6af92655fed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8a7b5adfcac0f46a4cd19da4ebb4a2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b83cb6327dcbc8a998e6586bcfa7a3b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d900531973c546625694146fa1509ab9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d054bdeb762f5b5ebf4d778fc8eed4ef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/29/0e4b05c1-9b0b-467b-ae26-0df311c9c19c.png?resizew=175)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c177e06cc3f703e8ca7be7c491fa2942.png)
(2)求直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/defa5b53043ae802bb1af7d14374406d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2cc6f6dfdbe7d39891c35f67e1a95c7f.png)
您最近一年使用:0次
4 . 如图,在四棱锥
中,底面
为直角梯形,
,
,![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a69df64811eb0866c84207f24dfae99.png)
,
,且
为
的中点,延长
交
于点
,且
在底
内的射影恰为
的中点
,
为
的中点,
为
上任意一点.
![](https://img.xkw.com/dksih/QBM/2020/1/3/2369332904345600/2369853049233408/STEM/06763c62-30e1-4c87-ae12-7fb6bafcbf3d.png)
(1)证明:平面
平面
;
(2)求平面
与平面
所成锐角二面角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6ab41c225644b3544608d5391698d49.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97e45b6f8cf0260912f587c04f9f2442.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/86c0ad79161fb29ec231dd0248623ed3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a69df64811eb0866c84207f24dfae99.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c41820837f147809527f692d7bad4e59.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ef8866ccf160ddc441bf69c5d3a3d5a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2c3d2cba96f6f03520c0b3f6e4da03e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a18722354086c42e62334983fc50eb6a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef4113c492885ba7c47fe42ac792578f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73465a1f9aa03481295bf6bd3c6903ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e26d9636ad77369535852c6e4493446a.png)
![](https://img.xkw.com/dksih/QBM/2020/1/3/2369332904345600/2369853049233408/STEM/06763c62-30e1-4c87-ae12-7fb6bafcbf3d.png)
(1)证明:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/097eb599df2710ab4fa78058ab68dbc7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0b14cf4977ee2dac0bd5b0fca4dadc3.png)
(2)求平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0b14cf4977ee2dac0bd5b0fca4dadc3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36a148a5584e41408fc74f8bd386b5b8.png)
您最近一年使用:0次
5 . 在三棱锥
中,已知
是等边三角形,
分别是
的中点,且
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/23/b019ad93-160c-4527-b827-23e98ece4a95.png?resizew=195)
(1)证明:
;
(2)求点
到平面
的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63397cda22cb1fad59cf966dfb588643.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aabe9e96020185b19868b392fc1e3a70.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2855505eaa7d24edecd05ffbd5df6bf7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aa364dffb98a94fb8285c2cdb9ad14b0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/31b2cc1d0bfd22c88286880b9da1f6f4.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/23/b019ad93-160c-4527-b827-23e98ece4a95.png?resizew=195)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3769377d3465909f32c98246e6776d9f.png)
(2)求点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
您最近一年使用:0次
名校
6 . 如图,在四棱锥
中,底面
是矩形,
,
,
底面
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/26/4543f909-17d5-427c-ba92-0b1894219849.png?resizew=151)
(1)当
为何值时,
平面
?证明你的结论;
(2)若在
边上至少存在一点
,使
,求
的取值范围.
![](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/fcd0ced286a0fbc7e4862f8147264277.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e781a2489271bfd1597cba1bb6f5887.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccd4fd4b7a4d6b8ca0c5827c055a9ce7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/26/4543f909-17d5-427c-ba92-0b1894219849.png?resizew=151)
(1)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a5928c98b341b16d4b5a5b931d2929d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0628681907ac8d7fdb94d8bc1b15feb9.png)
(2)若在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83abffb64a927cf133022dd88358e7a8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
您最近一年使用:0次
2020-01-03更新
|
1685次组卷
|
6卷引用:四川省南充市高中2019-2020学年高三第一次高考适应性考试数学(文)试题
四川省南充市高中2019-2020学年高三第一次高考适应性考试数学(文)试题(已下线)专题4.5 立体几何中探索性问题-玩转压轴题,进军满分之2021高考数学选择题填空题(已下线)专题31 直线、平面垂直的判定与性质-1陕西省西安市铁一中学2022-2023学年高二上学期1月期末数学试题2023版 湘教版(2019) 必修第二册 过关斩将 第4章 专题强化练6 空间中的垂直关系(已下线)10.3 直线与平面间的位置关系(第2课时)(七大题型)(分层练习)-2023-2024学年高二数学同步精品课堂(沪教版2020必修第三册)
7 . 在三棱锥
中,
是正三角形,面
面
,
,
,
、
分别是
、
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/27/30730022-8bb8-4f02-b6dd-ab2c7626ef13.png?resizew=154)
(1)证明:
;
(2)求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/41e5db1d2fd912f77923e4c120a7dc19.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/78307cd417504554a4e2276fe24d1162.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d2c15801fee2405573677484f5dcfa4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/55ca6072b3a2aac406a2b60bb7e01cde.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d4db9b82b67efe45a02fca32bfcf5dc.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/27/30730022-8bb8-4f02-b6dd-ab2c7626ef13.png?resizew=154)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/90fa715d27ae43ec1e157226bc9dea54.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6a5df4b7ea378e4463e0d7846a9f783e.png)
您最近一年使用:0次
2020-01-02更新
|
385次组卷
|
2卷引用:湖南省湖湘教育三新探索协作体2019-2020学年高二上学期12月联考数学试题
名校
8 . 已知
的三边长分别为
,
,
,M是AB边上的点,P是平面ABC外一点.给出下列四个命题:①若
平面ABC,则三棱锥
的四个面都是直角三角形;②若
平面ABC,且M是边AB的中点,则有
;③若
,
平面ABC,则
面积的最小值为
;④若
,P在平面ABC上的射影是
内切圆的圆心,则点P到平面ABC的距离为
.其中正确命题的序号是________ .(把你认为正确命题的序号都填上)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f08273d339dc5ddbb89aa67bb8205e6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e65a3e478bb87d094e3a0af30dd10ae8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d70dc2c20619a4fc12a0cfda59af5b69.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccd4fd4b7a4d6b8ca0c5827c055a9ce7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63397cda22cb1fad59cf966dfb588643.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a7442b64b37f685bc3ae88ff450c1a8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/30fc65a72853bd8ac1ad0828270d3baf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a43c2d5aae759fc4db16115c8188ceec.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5f1897a7e856b42f8cee0f286ad913d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1b28f2bfc52cde69845e3fe70cae49b5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7163395f9aaa29be7f6b3106ba48b744.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a43c2d5aae759fc4db16115c8188ceec.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/44ba5418a60abb24191ef4cabddc4fd8.png)
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2019-12-29更新
|
315次组卷
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2卷引用:吉林省延边二中2019-2020学年高一上学期12月月考数学试题
9 . 已知四棱锥
中,
,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/8/0aa1ff10-4b04-47db-a92c-d57ff890854d.png?resizew=201)
(1)求证:
;
(2)若
为线段
的中点,求三棱锥
的体积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/faeb97acf19bd3b2c6c77c2814df4d2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ee7781452f71281b6eb7d6da04295d70.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1b9e64665f1080ea5ca8a587dec45527.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2fe724734454d994d1e74b7b8a66e2a.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/8/0aa1ff10-4b04-47db-a92c-d57ff890854d.png?resizew=201)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0fe0bb7d51e559e73aa16a954fe7fa33.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c2bc5e50b8dfa02601c70822252854a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a52554625aae170696e167edddc45b00.png)
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2019-12-27更新
|
283次组卷
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3卷引用:百校联盟(全国I卷)2019-2020学年高三12月教育教学质量监测考试数学(文)试题
百校联盟(全国I卷)2019-2020学年高三12月教育教学质量监测考试数学(文)试题(已下线)2020届高三12月第03期(考点07)(文科)-《新题速递·数学》百校联盟2019-2020学年高三上学期教育教学质量监测考试文科数学
名校
10 . 在如图所示的几何体中,四边形
是等腰梯形
,
,
.在梯形
中,
,且
,
,
平面
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/8/c5ad7d0c-2ce9-432a-ab88-30811e08a624.png?resizew=149)
(Ⅰ)求证:
.
(II)求四棱锥
与三棱锥
体积的比值.
![](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/05740f0c6071846227dc0ec177ad15e8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4bf104481ef9b4675c733dbcc084b7b1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fd4b93d7abcfc4c3df48f03aa969c17f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/66784e61bb8be33243a208895fc2ae08.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3471bde9ec2c95cc301b4b3f468ca4aa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fe9131e7297c6c52cd962af9802f230b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f09ad78d4eccd1a9c9ccd3c4af79c79.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/8/c5ad7d0c-2ce9-432a-ab88-30811e08a624.png?resizew=149)
(Ⅰ)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/31025539da369c563e8633f375146593.png)
(II)求四棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c8ae27f6390d9f1ff55c54350caac510.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f26712d1a7a5864cd18498f16f7bd96c.png)
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