1 . 如图,在平行六面体
中,
,
,
,M,N分别为
,
中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/9/1e045548-b9c3-4a6d-b891-b810b9e2c4f6.png?resizew=185)
(1)求
的长;
(2)证明:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5441d73845911db1993bf903c4d8700f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f3e58edd1f900ca82bb2a3058293f52.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c6e7ac80553cc0af403a61741f3e351b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5fbafedc202bd0d86c4dfdece9f8f4fe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab35850dbc661ded6456b70767cc6cd0.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/9/1e045548-b9c3-4a6d-b891-b810b9e2c4f6.png?resizew=185)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24bb49fdc6b6bbb2449fdf8a0de769d3.png)
(2)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/72f88e1c3e5bb643bafcda8f20d6a9a7.png)
您最近一年使用:0次
解题方法
2 . 如图,在底面
为菱形的平行六面体
中,
分别在棱
上,且
,且
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/5/d28639fe-7514-4cd7-af15-c9af31164de1.png?resizew=168)
(1)求证:
共面;
(2)当
为何值时,
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7789a500686c7a73770404ead6af0590.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8e86e3991200297ad172455e5ea93f5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5cdcc0d2cbcf7ebf6975618f3114d51.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ba9196864f83e290af5ba64c4eb2c7ef.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/5/d28639fe-7514-4cd7-af15-c9af31164de1.png?resizew=168)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/606d331296842d04d46b1fa8d89219d0.png)
(2)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f6df10d0b03d6f6e640d9c5f3695a4e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a1515a445310d259a080d02e16c2e58e.png)
您最近一年使用:0次
3 . 如图,在四面体
中,E,F,G,H分别是
,
,
,
的中点.
![](https://img.xkw.com/dksih/QBM/2021/11/15/2851853284515840/2857634263597056/STEM/ce9abe65-c6eb-497e-9ebe-ca02ef97e411.png?resizew=242)
(1)若
,
,求证:
;
(2)设
,O为空间中任意一点,求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.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/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67d822262ff00915910e5b87d81ad1ba.png)
![](https://img.xkw.com/dksih/QBM/2021/11/15/2851853284515840/2857634263597056/STEM/ce9abe65-c6eb-497e-9ebe-ca02ef97e411.png?resizew=242)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56ee81929c987732fcb379802eeef7a7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e83ad09855a36ae1e8af3ecbd697db9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a77e3c1c236141d6118429fade0a9b9d.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/371ea12c470d1461a464c01636b71f8c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ec1696ba7e9fc3f3b9837032c87f7fc8.png)
您最近一年使用:0次
名校
解题方法
4 . 如图,在棱长为1的正四面体ABCD中,E是线段CD的中点,O在线段BE上,且
,设
,
,
.以
为基底,用向量法解决下列问题.
![](https://img.xkw.com/dksih/QBM/2021/10/13/2828540420612096/2830494755463168/STEM/20a775ab-fd80-4dfa-9ade-c1899ca4f795.png?resizew=224)
(1)用基底表示向量
;
(2)证明:
平面BCD;
(3)求点A到平面BCD的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/99ab92af3d8c902d3c671b997fd26c25.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4e7a93a1399ff7a2bde342652479241b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ae92f0c583cc9daf980a8621ad96aef5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/89f111250ea56c59b179cfc7b5db12cd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f8d2051594370095e72e173fd95888a.png)
![](https://img.xkw.com/dksih/QBM/2021/10/13/2828540420612096/2830494755463168/STEM/20a775ab-fd80-4dfa-9ade-c1899ca4f795.png?resizew=224)
(1)用基底表示向量
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a7f004f23ec3f968d885cb111aac4e2.png)
(2)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3ce03b310edce42191f9fa75a1c909ac.png)
(3)求点A到平面BCD的距离.
您最近一年使用:0次