如图, 已知四棱柱ABCD-A1B1C1D1的底面ABCD是正方形,CC1=3,CD=2,且∠C1CB=∠C1CD=60°.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/5/d32d9e8f-c04d-4667-9481-3ee55b9854f3.png?resizew=232)
(1)求证:BD⊥CA1;
(2)求CA1的长.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/5/d32d9e8f-c04d-4667-9481-3ee55b9854f3.png?resizew=232)
(1)求证:BD⊥CA1;
(2)求CA1的长.
更新时间:2022-11-04 12:53:16
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适中
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【推荐1】如图,在平行六面体
中,
,
,
,
,
,
,
与
相交于点
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/4/5221e899-1121-4c80-b14a-f8f7d31b4725.png?resizew=260)
(1)求
;
(2)求
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(3)求
的长.
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea77ee9aae8a89ab14e5cd8481b3747a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
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(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8bad16b7cdf8c638cd324f5be5d834f.png)
(2)求
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(3)求
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【推荐2】如图,棱长为
的正四面体(四个面都是正三角形)
,
是棱
的中点,点
在线段
上,点
在线段
上,且
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/2/09b147fe-ed07-4852-89df-e1a29c45165f.png?resizew=197)
(1)用向量
,
,
表示
;
(2)求
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdaa19de263700a15fcf213d64a8cd57.png)
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![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/2/09b147fe-ed07-4852-89df-e1a29c45165f.png?resizew=197)
(1)用向量
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d60dcb171bb7fd972aab8294d63acdb3.png)
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(2)求
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解题方法
【推荐1】如图,在棱长为3的正方体
中,点
是棱
上的一点,且
.
(1)若点
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平面
;
(2)底面
内是否存在一点
,使得
平面
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的长度;若不存在,请说明理由.
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a80440d52f529f92d6ab711b0aa93a8c.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/10/14/d29da3a7-4a71-475c-b7ff-96ba5b4fce45.png?resizew=172)
(1)若点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/673f20358c5745fd861590857cbc6198.png)
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(2)底面
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解答题-证明题
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【推荐2】如图,在三棱锥
中,
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(1)求证:
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(2)求
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(1)求证:
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(2)求
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