如图,在四棱锥
中,底面
是菱形,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/2/21/c37a4180-ee51-46a3-b12c-f20398a431b9.png?resizew=170)
(1)证明:
;
(2)若异面直线
与
所成角的余弦值为
,求平面
与平面
所成角的正弦值.
![](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/931bbffda5e872703c9947eccc47ede2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea4f5eec0addba78f2e0cdfb7ecc59a6.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/2/21/c37a4180-ee51-46a3-b12c-f20398a431b9.png?resizew=170)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cdfa54114f04a75b8c96165b3718ed7f.png)
(2)若异面直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aaa42621cd6793e7f3673fdb49bc3123.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83c7a937699f989b685f285041434000.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64c97bc6d754ac8cfbc7d5576edbb81a.png)
更新时间:2024-02-21 16:00:07
|
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解答题-证明题
|
适中
(0.65)
名校
解题方法
【推荐1】如图,在四棱锥
中,平面
底面
,底面
为平行四边形,
.
;
(2)在棱
上是否存在点
,使得![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2cdba1337ec85fa9722cb4b320a82ae6.png)
平面
?若存在,指出点
的位置;若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d077f6da8b2c00b152d4679aa2ed7f7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c828839ec7daffe75d61c24298afe7a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/352d85caf2bd9c6c66709d09df0ee0ac.png)
(2)在棱
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0629ce42392a7fe9be21d25c39c3e64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2cdba1337ec85fa9722cb4b320a82ae6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d67be899bc131ec1b9921ae9787c40d5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c66d99a6a8415ddad22bbed33b64cfb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
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解答题-证明题
|
适中
(0.65)
解题方法
【推荐2】如图,三棱柱
的底面是正三角形,
底面
,M为
的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/24/fd25ad21-150c-48aa-97cb-88d5506c9c73.png?resizew=182)
(1)求证:
平面
;
(2)若
,且沿侧棱
展开三棱柱的侧面,得到的侧面展开图的对角线长为
,求作点
在平面
内的射影H,请说明作法和理由,并求线段AH的长.
![](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/99b16cff607cdc2d69afc70dc778acbb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11ddc92d84d188c66b435664a7e7b5a4.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/24/fd25ad21-150c-48aa-97cb-88d5506c9c73.png?resizew=182)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/547a4b438e2e6687c7cd55ea08bbaae2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/46b91c857bbe3c4f0f08dd2a4124a96e.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2cc416a5b8dc234628e7475387888d82.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0a851907ada2ac2c3c4880a6736d28a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3dafaeda9177baa0f937f58f680de448.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a18722354086c42e62334983fc50eb6a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/46b91c857bbe3c4f0f08dd2a4124a96e.png)
您最近一年使用:0次
解答题-问答题
|
适中
(0.65)
解题方法
【推荐1】如图.四棱柱ABCD-A1B1C1D1的底面是直角梯形,BC∥AD,ABAD,AD=2BC=2,四边形ABB1A1和ADD1A1均为正方形.
![](https://img.xkw.com/dksih/QBM/2021/1/23/2642302918057984/2644381425926144/STEM/2c1a227895b24f4389550fd1a7fc8197.png?resizew=150)
(1)证明;平面ABB1A1平面ABCD;
(2)求二面角B1 CD-A的余弦值.
![](https://img.xkw.com/dksih/QBM/2021/1/23/2642302918057984/2644381425926144/STEM/2c1a227895b24f4389550fd1a7fc8197.png?resizew=150)
(1)证明;平面ABB1A1平面ABCD;
(2)求二面角B1 CD-A的余弦值.
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解答题-证明题
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适中
(0.65)
【推荐2】如图所示,在正四棱锥
中,底面ABCD的中心为O,PD边上的垂线BE交线段PO于点F,
.
(1)证明:
//平面PBC;
(2)求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4060489388a45c7f697de96a69e13aa7.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/8/9/2a41dc80-089f-480e-823b-dff0e3d78910.png?resizew=167)
(1)证明:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f90c780dac29ff8b7df5881d3b33abab.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b33b7213d99a817bff19bcf740a0697c.png)
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