解题方法
1 . 如图,在四棱锥
中,侧面
底面
,底面ABCD是矩形,
, E,F分别是棱PC,PD的中点.
![](https://img.xkw.com/dksih/QBM/2019/11/28/2343719880220672/2394537964994560/STEM/322784e87f4f4274a39d233c4ff4a91e.png?resizew=299)
(Ⅰ)求证:
;
(Ⅱ)求证:
平面
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a4426db778693c875e2dca9220875d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93edc7bb513f40a89173121c8570cd65.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e3f6967901d6c855864df01e7bf7a15c.png)
![](https://img.xkw.com/dksih/QBM/2019/11/28/2343719880220672/2394537964994560/STEM/322784e87f4f4274a39d233c4ff4a91e.png?resizew=299)
(Ⅰ)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eb8df9fecaa0b266568ad35fb8f0e019.png)
(Ⅱ)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6a22d6b860f06fe23618b0d3de6768fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80f747eb5b2d21c9de962cbfd4ec4bb7.png)
您最近一年使用:0次
2 . 如图,在四棱锥
中,
,底面ABCD是边长为3的正方形,E、F、G分别是棱AB、PB、PC的中点,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/2/39e82a74-0307-418f-83b2-b98235dee163.png?resizew=292)
(Ⅰ)求证:平面EFG∥平面PAD;
(Ⅱ)求三棱锥
的体积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a4426db778693c875e2dca9220875d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cbb05b8b630052ff544249ebd72d95d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c19f0fcacac715a1200770516d1e4a67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f8d0f60d9856f286e537788a99377590.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/2/39e82a74-0307-418f-83b2-b98235dee163.png?resizew=292)
(Ⅰ)求证:平面EFG∥平面PAD;
(Ⅱ)求三棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/98ad0298c0f7878cb7c4dd7a141cd952.png)
您最近一年使用:0次
3 . 如图,在三棱柱
中,
,
,
,D是棱BC的中点,E是侧面四边形
的对角线
的中点.
![](https://img.xkw.com/dksih/QBM/2019/11/28/2343720216010752/2394508680888320/STEM/f194f152b5d74224b8cbd6e6071f545c.png?resizew=144)
(Ⅰ)求证:
平面
;
(Ⅱ)求证:
平面
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/22baaea72c9286f1d8d7b99c37755678.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/615fc8790237a1b09af51d6bcad6b595.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc0a886f1192d450ced9fd875e78425e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/46fe926770d2354e172dec02f5ce2efe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d9a8181f7a7fe7f3fac872ce9534f15.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3ee8456443402a25b1e25d35ff7e1c98.png)
![](https://img.xkw.com/dksih/QBM/2019/11/28/2343720216010752/2394508680888320/STEM/f194f152b5d74224b8cbd6e6071f545c.png?resizew=144)
(Ⅰ)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/063510e3c1fb6a7ccc3b8e3e3c7d660e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab3e0dba5705e1d749cfb21ebbb2ed93.png)
(Ⅱ)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f4c3f9dd5d0343597a7f58a1989b537.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9afac7c616bbb14e1ed428a3c507c7dc.png)
您最近一年使用:0次