1 . 如图1,已知菱形
的对角线![](https://staticzujuan.xkw.com/quesimg/Upload/formula/178a2a5f277bab230e7e65ee5b8b53a1.png)
交于点
,点
为
的中点.将三角形
沿线段
折起到三角形
的位置,如图2所示.
(1)求证:
平面
;
(2)证明:平面
平面
;
(3)在线段
上是否分别存在点
,使得平面
平面
?若存在,请指出点
的位置,并证明;若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d6bfad3f7e65188bcf7f62ea5acdbf4a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/178a2a5f277bab230e7e65ee5b8b53a1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.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/b9a32bd7a1b78b5a0ec562c4025aea8c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b37793a3a810e823e10c340986f55ddd.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/5/31/0c8ed141-e18a-444a-84f5-bac476792bec.png?resizew=363)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8d2d217e9bcd059908f117dfc4d4259.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/149596fee6ed1e2d19fd8dadc14a8baf.png)
(2)证明:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/78a3fd5284e160896f07ce367645fd04.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/149596fee6ed1e2d19fd8dadc14a8baf.png)
(3)在线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1457d2e76a5b86de1abf121c51eb9d35.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7789a500686c7a73770404ead6af0590.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42bda8898cce4936691bb5ec6579c07c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bcbc9387f41c6f138c40de12588eb86d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7789a500686c7a73770404ead6af0590.png)
您最近一年使用:0次
2018-05-04更新
|
1675次组卷
|
5卷引用:【全国市级联考】北京市海淀区2018届高三第二学期期末练习(二模)数学(文)试题
【全国市级联考】北京市海淀区2018届高三第二学期期末练习(二模)数学(文)试题(已下线)2018年10月11日 《每日一题》一轮复习理数-空间线面位置关系(2)(已下线)2018年10月17日 《每日一题》一轮复习(文数)-空间线面位置关系(2)苏教版(2019) 必修第二册 过关斩将 第13章 13.2 综合拔高练(已下线)第18讲 基本图形位置关系
2 . 如图,在三棱柱
中,
底面
,
,
,
,
是棱
的中点.
(Ⅰ)求证:
平面
;
(Ⅱ)求三棱锥
的体积;
(Ⅲ)在线段
上是否存在点
,使得
?请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ede6a60cad0e0b58e1549fda6e085719.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/326a3339175592bd1e793a9054d57fe5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/787ac5e13622afab5e9f8603afe42356.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/82da6815bc213dfd78c2f77cd7ded8ed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/525c082c493ba275001f38dc748b7b65.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3cd34ae1a0406994d2c07a61e9220a3b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0c640abbdc470479407da1ae2aa80fb.png)
(Ⅰ)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8278c4ce726252b41adb440f18132f33.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/01e04a5b59cced25ab7057d03fe3c0ad.png)
(Ⅱ)求三棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3c4bfd5fce8d8415c7a9d23973fcae65.png)
(Ⅲ)在线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3182db896bc2462331796e2a6108363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc081e71a45e6fb2731fd68e91ee72e3.png)
![](https://img.xkw.com/dksih/QBM/2017/5/11/1684912517758976/1685482264059904/STEM/c4c98a6510644548b010f56ebbc94431.png?resizew=257)
您最近一年使用:0次
3 . 如图,在三棱柱中,侧面
是矩形,
,
,
,且
![](https://img.xkw.com/dksih/QBM/editorImg/2022/9/6/fc5812d0-79a6-477a-bea9-a91a591417f8.png?resizew=149)
(1)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/140088b0cb73812aa9d523c44559298a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/31e53b212640dadf751ef7f65a78a209.png)
(2)设D是
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f1f229274a6e17977cc047814212589.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0a851907ada2ac2c3c4880a6736d28a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/063510e3c1fb6a7ccc3b8e3e3c7d660e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea848cd2aa3a464618020475097949fc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea848cd2aa3a464618020475097949fc.png)
您最近一年使用:0次
2017-02-08更新
|
1511次组卷
|
4卷引用:【全国百强校】北京师范大学附属中学2019届高三(下)四月份月考数学(文科)试题(五)
4 . 如图,四棱锥
中,底面
是边长为 4的菱形,
,
,
为
中点.
![](https://img.xkw.com/dksih/QBM/2016/3/4/1572518713155584/1572518718963712/STEM/2d0a5c44c5294384ba697fd8c1b2494c.png?resizew=223)
(1)求证:
平面
;
(2)求证:平面![](https://staticzujuan.xkw.com/quesimg/Upload/formula/65277734669566578cbb7d690bb200fb.png)
平面
;
(3)若
,求三棱锥
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/f75cf0288e9b7c31a426aff6b91a5a8e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b86db010859f7a243badec02946a4e24.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bd33764ff4efddfe11a98a609753715c.png)
![](https://img.xkw.com/dksih/QBM/2016/3/4/1572518713155584/1572518718963712/STEM/2d0a5c44c5294384ba697fd8c1b2494c.png?resizew=223)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1b70cef0b79ca64acbb67dc667fc53b3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/65277734669566578cbb7d690bb200fb.png)
(2)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/65277734669566578cbb7d690bb200fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1633988fd62a652de726ee92a917b52d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0628681907ac8d7fdb94d8bc1b15feb9.png)
(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8cb96e0331eebe80ed1ff610faf531fe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/578fc8dd7d45fd2799f7d05ac89a2024.png)
您最近一年使用:0次
2016-12-04更新
|
1422次组卷
|
2卷引用:2016届北京市丰台区高三上学期期末联考文科数学试卷
解题方法
5 . 如图所示,正方体
的棱长为1,
分别是棱
,
的中点,过直线
的平面分别与棱
、
交于
,设
,
,给出以下四个命题:
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/8/5c53e251-4346-4998-867d-e1e90759f9d7.png?resizew=224)
①四边形
为平行四边形;
②若四边形
面积
,则
有最小值;
③若四棱锥
的体积![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e61eac79ec7913fc950226db18915308.png)
,
,则
常函数;
④若多面体
的体积
,
,则
为单调函数.
其中假命题为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3da8c338342e38c9aa3f274c053fd5b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad056c25c0fdcbcc765eb5cbc6093f2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6024fd4532f5f981deac4582c799a6ef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20ecac2dad4cffdd971fd23deacff3fc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ad056c25c0fdcbcc765eb5cbc6093f2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6655cc150ddc9deba2254780984d0024.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/82b25f3ea33cc08b1e2a0d9c3a9dccaf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7789a500686c7a73770404ead6af0590.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4af217fbffcef5bd43e1fdc8a7bd6220.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c7b69e93488fcd2a195cb9793e94fc7.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/8/5c53e251-4346-4998-867d-e1e90759f9d7.png?resizew=224)
①四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/65e92eac740953aa383be636ea90fd47.png)
②若四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/65e92eac740953aa383be636ea90fd47.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0d4ef9a0424161728f65356fa02620b3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fe7d5809da02c15a43a0e9a898b9086.png)
③若四棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b941daa059b04aab552429ae22a1661d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e61eac79ec7913fc950226db18915308.png)
![](https://img.xkw.com/dksih/QBM/2016/3/4/1572517993783296/1572517999558656/STEM/f6002b804c144dcd95df67c5839e8c6e.png?resizew=12)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c7b69e93488fcd2a195cb9793e94fc7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/27c97d54952104950bfd7afc0176bbd0.png)
④若多面体
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21d806315045c99f270687030c61cd8c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e3b11baa5184a3f07f167cc328f1abf1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/37bc347c13a4d4171648cad72b96e796.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0eb7df298a9364b36e079a61caec815c.png)
其中假命题为
A.① | B.② | C.③ | D.④ |
您最近一年使用:0次
2011·北京西城·一模
6 . 如图,
是边长为
的正方形,
平面
,
,
,
与平面
所成角为
.
![](https://img.xkw.com/dksih/QBM/2015/9/25/1572241494597632/1572241500585984/STEM/c2dd45c4ba1646c69e090be9382caaf5.png)
(Ⅰ)求证:
平面
;
(Ⅱ)求二面角
的余弦值;
(Ⅲ)设点
是线段
上一个动点,试确定点
的位置,使得
平面
,并证明你的结论.
![](https://img.xkw.com/dksih/QBM/2015/9/25/1572241494597632/1572241500585984/STEM/fe701b53575443c292db4d872e40ef05.png)
![](https://img.xkw.com/dksih/QBM/2015/9/25/1572241494597632/1572241500585984/STEM/2a3e33d681e842f8b71707d3b573487c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/05638d82225327da27e5f916d2d4e747.png)
![](https://img.xkw.com/dksih/QBM/2015/9/25/1572241494597632/1572241500585984/STEM/fe701b53575443c292db4d872e40ef05.png)
![](https://img.xkw.com/dksih/QBM/2015/9/25/1572241494597632/1572241500585984/STEM/4ff673aaecc44d63acbd5c98d6eac0a3.png)
![](https://img.xkw.com/dksih/QBM/2015/9/25/1572241494597632/1572241500585984/STEM/527f9ac3d51e4280b1e8f14331835f42.png)
![](https://img.xkw.com/dksih/QBM/2015/9/25/1572241494597632/1572241500585984/STEM/b0a0b01103ed4e7b9373b12fcb75fef5.png)
![](https://img.xkw.com/dksih/QBM/2015/9/25/1572241494597632/1572241500585984/STEM/fe701b53575443c292db4d872e40ef05.png)
![](https://img.xkw.com/dksih/QBM/2015/9/25/1572241494597632/1572241500585984/STEM/7ae9bad96345493fb94386207d35553e.png)
![](https://img.xkw.com/dksih/QBM/2015/9/25/1572241494597632/1572241500585984/STEM/c2dd45c4ba1646c69e090be9382caaf5.png)
(Ⅰ)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/599b63c003aeb99d777e87182db8f019.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/34be4e71cabf458f17a6cd7f24bc70af.png)
(Ⅱ)求二面角
![](https://img.xkw.com/dksih/QBM/2015/9/25/1572241494597632/1572241500585984/STEM/8162eff6ad1c42db89028790e9e2fb4f.png)
(Ⅲ)设点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8ac480d8d9d7821b62a603cf5cfda236.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/87c0bfeadcf17b2a45896071f07a4a5a.png)
您最近一年使用:0次
7 . 如图,正方形
与梯形
所在的平面互相垂直,
,
,
,
,
为
的中点.
(1)求证:
平面
;
(2)求证:平面
平面
;
(3)求平面
与平面
所成锐二面角的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3ecc1cb55a57dde481f8dd07ab150676.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cdb2dd10731b99c0f4f89ee957f8a239.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b37591109b0a0ec5ffe2133f83310eca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/27db558e8db4c957654c8e5cecd2d2dc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e673ef2d48215ca84a48377f17d6df00.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/9/30/27396d36-39a5-417e-a0a1-bbd7128408ec.png?resizew=192)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2061b9ab3862d9c36d32c4ffef91145a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3ecc1cb55a57dde481f8dd07ab150676.png)
(2)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3547a914468b082d8d8741b974a03190.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e9a814b70236a108be5d6e7ff271fe92.png)
(3)求平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e9a814b70236a108be5d6e7ff271fe92.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3ecc1cb55a57dde481f8dd07ab150676.png)
您最近一年使用:0次
2016-12-03更新
|
2290次组卷
|
5卷引用:2011届北京市东城区高三上学期期末理科数学卷
2014·北京房山·一模
名校
8 . 如图,三棱柱
中,
平面
,
,
,
,以
,
为邻边作平行四边形
,连接
和
.
![](https://img.xkw.com/dksih/QBM/2014/5/12/1571712601071616/1571712607068160/STEM/625373d6-e844-43c7-a40f-acb2883d026f.png?resizew=193)
(Ⅰ)求证:
平面
;
(Ⅱ)求直线
与平面
所成角的正弦值;
(Ⅲ)线段
上是否存在点
,使平面
与平面
垂直?若存在,求出
的长;若不存在,说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5845ccc0d735dc14c92a8926d9b1def6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed10df4140819d5451773a45de66201b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7ad3a578f403b9e6b97fa2dc955fc11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/92535536bd3c2761724fd058427f95a8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e75d14708e6aa1404477db9d7e3166f0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f2eb89294b31ffdd2680b4361e8994d7.png)
![](https://img.xkw.com/dksih/QBM/2014/5/12/1571712601071616/1571712607068160/STEM/625373d6-e844-43c7-a40f-acb2883d026f.png?resizew=193)
(Ⅰ)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4ac809549102844f24d73a5bfdf2464.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e168672b47d7e64dc1b404f8882c7dcf.png)
(Ⅱ)求直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d88bf46ad08f9677c37eed1d0369329.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cee3d1518e197f7f25c341da6b1e3483.png)
(Ⅲ)线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cee3d1518e197f7f25c341da6b1e3483.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8ee076fe7dbca5616c4e8a6869a355f4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/274cf35acb4a1748d15c39d15a9bea7b.png)
您最近一年使用:0次
2016-12-03更新
|
5895次组卷
|
3卷引用:2014届北京市房山区4月高三一模理科数学试卷
13-14高三·北京西城·期末
9 . 如下图,在四棱柱
中,底面
和侧面
都
是矩形,
是
的中点,
,
.
(1)求证:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8eb7548af8fc8192e7fd5d1c728681a8.png)
(2)求证:
平面
;
(3)若平面
与平面
所成的锐二面角的大小为
,求线段
的长度.![](https://img.xkw.com/dksih/QBM/2014/4/24/1571654083198976/1571654089015296/STEM/3426770ec8dd485a92c3be89f6ccc3d7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8456cee87c4e22351affc28f3a73a0f2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e168672b47d7e64dc1b404f8882c7dcf.png)
是矩形,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b5c67745fcf0a5978e01722cb3e07a1.png)
![](https://img.xkw.com/dksih/QBM/2014/4/24/1571654083198976/1571654089015296/STEM/bfe6a75e57c54f939e03e4a0706d7a7d.png)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8eb7548af8fc8192e7fd5d1c728681a8.png)
(2)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/504a36c231b8e80724d01649e7c0944f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9a83c0b8db2205a6815811aa4ff5390f.png)
(3)若平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e168672b47d7e64dc1b404f8882c7dcf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9a83c0b8db2205a6815811aa4ff5390f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ecdab625e32e38d1c72c901cece0e147.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15dc61d5de97b5a40be925b278ae494c.png)
![](https://img.xkw.com/dksih/QBM/2014/4/24/1571654083198976/1571654089015296/STEM/3426770ec8dd485a92c3be89f6ccc3d7.png)
![](https://img.xkw.com/dksih/QBM/2014/4/24/1571654083198976/1571654089015296/STEM/bfa1e661d2fd4e7d894765caefe65f72.png)
您最近一年使用:0次