如图1,在高为2的梯形
中,
,
,
,过
、
分别作
,
,垂足分别为
、
.已知
,将梯形
沿
、
同侧折起,得空间几何体
,如图2.
![](https://img.xkw.com/dksih/QBM/2017/7/7/1725037203406848/1726250220175360/STEM/fe793d1403db4238b6595ca2026fab09.png?resizew=435)
(1)若
,证明:
为直角三角形;
(2)若
,证明:
平面
;
(3)在(1),(2)的条件下,求三棱锥
的体积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f79863ffcfa63117ca6741b20a48e69.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcd0ced286a0fbc7e4862f8147264277.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b515965c22d2950b592c096c6e3bdfd4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e4611ceb2a28f7a7e4d24266d7f99b22.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a1ff7bf8ffc8a04186e3e13c1a6d5ced.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/82773737609e65dea3c5c67099f1b10d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/274cf35acb4a1748d15c39d15a9bea7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/535770901287f244911b42412533d4a9.png)
![](https://img.xkw.com/dksih/QBM/2017/7/7/1725037203406848/1726250220175360/STEM/fe793d1403db4238b6595ca2026fab09.png?resizew=435)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e39b13d187b25461d85a3b8d10c7b678.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/321370fe42bc1216902ea19fbd2a5979.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dced11455b3e31a9090915f80a046fa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c372d059202ec388960b125d4a87dc84.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b4eb7e9ad5486cf1c5e506b20c5469e8.png)
(3)在(1),(2)的条件下,求三棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c41ffdaecfb3c73d403179e5745c71a8.png)
更新时间:2017-07-09 08:07:58
|
相似题推荐
解答题-证明题
|
适中
(0.65)
解题方法
【推荐1】如图,已知三棱柱ABC﹣A1B1C1中,AA1⊥底面ABC,AC=BC=2,AA1=4,
,M,N分别是棱CC1,AB中点.
![](https://img.xkw.com/dksih/QBM/2016/3/4/1572519727022080/1572519733190656/STEM/9cf3f759-1b59-48fb-9774-d0e051fb12a2.png?resizew=160)
(Ⅰ)求证:CN⊥平面ABB1A1;
(Ⅱ)求证:CN∥平面AMB1;
(Ⅲ)求三棱锥B1﹣AMN的体积.
![](https://img.xkw.com/dksih/QBM/2016/4/18/1572595750387712/1572595756064768/STEM/e2bd4d3e7bcc4f789898599444da59fd.png)
![](https://img.xkw.com/dksih/QBM/2016/3/4/1572519727022080/1572519733190656/STEM/9cf3f759-1b59-48fb-9774-d0e051fb12a2.png?resizew=160)
(Ⅰ)求证:CN⊥平面ABB1A1;
(Ⅱ)求证:CN∥平面AMB1;
(Ⅲ)求三棱锥B1﹣AMN的体积.
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【推荐2】如图,在四棱锥
中,侧棱
底面
,底面
为矩形,且
,
是
的中点,作
交
于点
.
![](https://img.xkw.com/dksih/QBM/2018/5/20/1949494812516352/1949927917142016/STEM/50a18d6b55684ecc9fc9a4db48dd61f5.png?resizew=213)
(1)证明:
平面
;
(2)若三棱锥
的体积为
,求直线
与平面
所成角的正弦值;
(3)在(2)的条件下,求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.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/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a5e84a62b385350e02a534046d6acf03.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9a4a6a1e70241d600bc6c104313eac61.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://img.xkw.com/dksih/QBM/2018/5/20/1949494812516352/1949927917142016/STEM/50a18d6b55684ecc9fc9a4db48dd61f5.png?resizew=213)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c45fbffb9e2c7fa7c5006cde8da0cabe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/134ef0b1a2669a09f05bd4dc2496f706.png)
(2)若三棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/398243832c62535aecf7a812e482afd0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4dac452fbb5ef6dd653e7fbbef639484.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/134ef0b1a2669a09f05bd4dc2496f706.png)
(3)在(2)的条件下,求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a821b45899e2f07e99d315f583571c7.png)
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【推荐1】已知四棱锥
的底面为直角梯形,
,
,
平面
,
.
是棱
上靠近
的三等分点,证明:
平面
;
(2)试探究棱
上是否存在一点
(不与
、
重合),使得平面
平面
?若存在,请求出
的值;若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcd8e727e4efc22b49649f71ae9c9d84.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2b377f22aafd3742ad860f77abaacef.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/bda1a7eeb84ee2f5f723c78de0867aa1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/826bf6fa3706921b77ad0eb4fcc206bd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af68a7bf0da4f7c6f739d2e2461ad9b7.png)
(2)试探究棱
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c8514dbf5eec5b2bff253c13e33fd09.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bfaf581b4f42a25087f7eee23a7d66b6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/50cafe199913787a939fe9e100924023.png)
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解答题-问答题
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适中
(0.65)
名校
解题方法
【推荐2】如图,正方形
和矩形
所在平面互相垂直,
,
,
为
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/4/b70209b7-1e82-43c7-8ae2-8785bc938df4.png?resizew=161)
(1)证明:平面
平面
;
(2)证明:
平面
;
(3)求点
到平面
的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fd4b93d7abcfc4c3df48f03aa969c17f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcd0ced286a0fbc7e4862f8147264277.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/27ba952c1209a61b00cc62aacb367292.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/4/b70209b7-1e82-43c7-8ae2-8785bc938df4.png?resizew=161)
(1)证明:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d98d25467d8a11ddeeb1e6e18eb704f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/422210c777ac0d625bbd81cc7601bf9b.png)
(2)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8ac480d8d9d7821b62a603cf5cfda236.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/34be4e71cabf458f17a6cd7f24bc70af.png)
(3)求点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ae8768996ca9a0f2c5d9a19abbd54df.png)
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解题方法
【推荐3】如图,在三棱锥D-ABC中,已知△BCD是正三角形,AB⊥平面BCD,AB=BC=a,E为BC中点,F在棱AC上,且AF=3FC.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/25/942e8879-7ce6-40cc-86e4-946736292f4a.png?resizew=171)
(1)求三棱锥D-ABC的体积;
(2)求证:AC⊥平面DEF;
(3)若M为DB中点,N在棱AC上,且
求证:MN//平面DEF.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/25/942e8879-7ce6-40cc-86e4-946736292f4a.png?resizew=171)
(1)求三棱锥D-ABC的体积;
(2)求证:AC⊥平面DEF;
(3)若M为DB中点,N在棱AC上,且
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c3e0a8c39971e1059a6c8940bd6189f.png)
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【推荐1】如图,在三棱台ABC-DEF中,AB=BC=AC=2,AD=DF=FC=1,N为DF的中点,二面角D-AC-B的大小为
.
![](https://img.xkw.com/dksih/QBM/2017/2/16/1625399184465920/1625951221760000/STEM/825a3650-bd2f-471b-857a-99da46c42e18.png)
(Ⅰ)证明:
;
(Ⅱ)求直线AD与平面BEFC所成角的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f785147690f83dcee0a0bc6c327e75a.png)
![](https://img.xkw.com/dksih/QBM/2017/2/16/1625399184465920/1625951221760000/STEM/825a3650-bd2f-471b-857a-99da46c42e18.png)
(Ⅰ)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/adf21399dcf3682bf5d3f9cbd5eed86c.png)
(Ⅱ)求直线AD与平面BEFC所成角的正弦值.
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名校
解题方法
【推荐2】如图,
是圆
的直径,点
是圆
上异于
的点,直线
平面
,
分别是
,
的中点.
(1)记平面
与平面
的交线为
,试判断直线
与平面
的位置关系,并加以证明;
(2)设
,求三棱锥
的体积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01c74a907dda6bb7d9d56d009d9df253.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5f1897a7e856b42f8cee0f286ad913d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad056c25c0fdcbcc765eb5cbc6093f2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bd33764ff4efddfe11a98a609753715c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
(1)记平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/87c0bfeadcf17b2a45896071f07a4a5a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0628681907ac8d7fdb94d8bc1b15feb9.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/739b1beecbbb34ae69015110e9fcd2ae.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/90da0522dd9378bab25de2f560aec563.png)
![](https://img.xkw.com/dksih/QBM/2017/11/13/1816209236254720/1816495191285760/STEM/3135fda39f2a44be83138c664fa8d1c0.png?resizew=193)
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