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1 . 如图,已知正四棱锥
与正四面体
所有的棱长均为
.
![](https://img.xkw.com/dksih/QBM/2021/7/8/2759751319707648/2777760744325120/STEM/ede128cb-f7cd-45e0-b834-efbf130c4aef.png?resizew=477)
(1)若
为
的中点,证明:
平面
;
(2)把正四面体
与正四棱锥
全等的两个面重合,排成一个新的几何体,问该几何体由多少个面组成?并说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/faeb97acf19bd3b2c6c77c2814df4d2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/858d5bfe390d0cb79cee200241240a31.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://img.xkw.com/dksih/QBM/2021/7/8/2759751319707648/2777760744325120/STEM/ede128cb-f7cd-45e0-b834-efbf130c4aef.png?resizew=477)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d4db9b82b67efe45a02fca32bfcf5dc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca6d50356a01ae13936f1bd8efa94c98.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fb304d905125170bebfada27e7ed8960.png)
(2)把正四面体
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/858d5bfe390d0cb79cee200241240a31.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/faeb97acf19bd3b2c6c77c2814df4d2f.png)
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2021-08-02更新
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889次组卷
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3卷引用:四川省成都第七中学2021-2022学年高二上学期入学数学(理科)试题