如图,在四棱锥P-ABCD中,底面ABCD是正方形,侧棱PD⊥底面ABCD,PD=DC,E是PC的中点.
![](https://img.xkw.com/dksih/QBM/2021/5/6/2715351937728512/2799687618240512/STEM/7462a2c145664a249acbe5bf2abc7d60.png?resizew=235)
(1)证明:PA//平面EDB;
(2)证明:DE⊥平面PBC.
![](https://img.xkw.com/dksih/QBM/2021/5/6/2715351937728512/2799687618240512/STEM/7462a2c145664a249acbe5bf2abc7d60.png?resizew=235)
(1)证明:PA//平面EDB;
(2)证明:DE⊥平面PBC.
更新时间:2021-09-02 22:41:57
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解答题-问答题
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适中
(0.65)
解题方法
【推荐1】如图,在四棱锥
中,平面
底面
,底面
为正方形,
为
的中点,
为
的中点.
//底面
;
(2)已知
,二面角
的平面角为
,求四棱锥
的体积.
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(2)已知
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解答题-证明题
|
适中
(0.65)
【推荐2】如图所示,四边形
为菱形,
平面
,
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(Ⅰ)求证:
平面
;
(Ⅱ)当
为何值时,直线
平面
?请说明理由.
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(Ⅱ)当
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解答题-问答题
|
适中
(0.65)
【推荐1】如图,在三棱锥
中,底面
为梯形,
,点
在底面
内的正投影为点
,且
为
的中点.
(1)证明:
平面
;
(2)若
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的体积.
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(2)若
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解答题-问答题
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适中
(0.65)
【推荐2】如图,三棱柱
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平面
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,
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,
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