如图,
中,
是
的中点,
,
.将
沿
折起,使
点与图中
点重合.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/047dc9795efa99b6fb9fdf9778085dab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a63b2c21bd66fe36fd726d17a338fdda.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aef7d7abc808c38173ea94c60e098ae2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2c3d2cba96f6f03520c0b3f6e4da03e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://img.xkw.com/dksih/QBM/2017/5/8/1682481531576320/1689161281200128/STEM/60f1b52b6da84fa3975a1bce9579f4fd.png?resizew=17)
(Ⅰ)求证:;
(Ⅱ)当三棱锥的体积取最大时,求二面角
的余弦值;
(Ⅲ)在(Ⅱ)的条件下,试问在线段上是否存在一点
,使
与平面
所成的角的正弦值为
?证明你的结论.
![](https://img.xkw.com/dksih/QBM/2017/5/8/1682481531576320/1689161281200128/STEM/c656a068d94849ffbfdaca92a6e870f9.png?resizew=160)
2014·浙江·一模 查看更多[2]
更新时间:2016-12-03 07:44:31
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相似题推荐
解答题-证明题
|
较难
(0.4)
【推荐1】如图,四棱锥
中,
,底面
为梯形,
,
,且
,
.
![](https://img.xkw.com/dksih/QBM/2015/3/12/1572003940409344/1572003946422272/STEM/60bac04abdf240f1adb5aa7f99e3180e.png)
(1)求证:
;
(2)求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6153163fecdf3f410411048428ccaef5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/69f448b5ea52ae7d0ee6c2c028b8993d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68d31600cba2d5256c7e78b6122d6755.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6c38d26d85081a99d51e2f686817e94.png)
![](https://img.xkw.com/dksih/QBM/2015/3/12/1572003940409344/1572003946422272/STEM/b744886c5b394fc2909d62d313bfb99d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ddd3a955619c47a1bf66dfb27da3d24.png)
![](https://img.xkw.com/dksih/QBM/2015/3/12/1572003940409344/1572003946422272/STEM/60bac04abdf240f1adb5aa7f99e3180e.png)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04c076da2f5838d3a7ffd62658150153.png)
(2)求二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2d0e5e87b6c81dab9e1ce0d3b79992f.png)
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解答题-证明题
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较难
(0.4)
【推荐2】如图,在四棱锥
中,
底面
为直角梯形,
,
,且![](https://img.xkw.com/dksih/QBM/2016/6/7/1572707795550208/1572707801669632/STEM/a902ab458bdd48a6b754f2fa5371f01c.png)
![](https://img.xkw.com/dksih/QBM/2016/6/7/1572707795550208/1572707801669632/STEM/dbe0919b468047ac8b36049b72f8ce18.png)
(1)求证:平面
平面![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc9c9cfa597b444b5c9dbae7a825a695.png)
(2)若E、F分别为线段
上的一点(端点除外),满足
,是否存在
使得
为直角三角形,若存在求出所有满足条件的
,若不存在,请说明理由.
![](https://img.xkw.com/dksih/QBM/2016/6/7/1572707795550208/1572707801669632/STEM/18e63ce4b50d4e96a5487aaf22faab68.png)
![](https://img.xkw.com/dksih/QBM/2016/6/7/1572707795550208/1572707801669632/STEM/53a65fe0f0b546879923e2ccb749d129.png)
![](https://img.xkw.com/dksih/QBM/2016/6/7/1572707795550208/1572707801669632/STEM/ffbd24347f984f83b315488097d5bf5e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f571396be1aa4a8914a66f7d7abd6381.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/16f0b207d724137d768e4370a122f047.png)
![](https://img.xkw.com/dksih/QBM/2016/6/7/1572707795550208/1572707801669632/STEM/a902ab458bdd48a6b754f2fa5371f01c.png)
![](https://img.xkw.com/dksih/QBM/2016/6/7/1572707795550208/1572707801669632/STEM/dbe0919b468047ac8b36049b72f8ce18.png)
(1)求证:平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/809c217376eadf99d1b324fc403b16c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc9c9cfa597b444b5c9dbae7a825a695.png)
(2)若E、F分别为线段
![](https://img.xkw.com/dksih/QBM/2016/6/7/1572707795550208/1572707801669632/STEM/c96ed58b24e44de2be2a4e86569ee1f6.png)
![](https://img.xkw.com/dksih/QBM/2016/6/7/1572707795550208/1572707801669632/STEM/7f19665fda6c470bbc6139f9f9fc535f.png)
![](https://img.xkw.com/dksih/QBM/2016/6/7/1572707795550208/1572707801669632/STEM/a785030a060349c288e7ddc156b0905e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/425e79e4e7c13e2ea8ae3d4f8d31ac33.png)
![](https://img.xkw.com/dksih/QBM/2016/6/7/1572707795550208/1572707801669632/STEM/a785030a060349c288e7ddc156b0905e.png)
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解答题-问答题
|
较难
(0.4)
【推荐2】如图,在三棱柱ABC﹣A1B1C1中,∠BAC=90°,AB=AC=2,AA1=4,A1在底面ABC的射影为BC的中点E,D是B1C1的中点.
![](https://img.xkw.com/dksih/QBM/2016/3/11/1572532911251456/1572532917149696/STEM/e6e568d68d4442409511d2ff8abede5d.png)
(1)证明:A1D⊥平面A1BC;
(2)求点B到平面A1ACC1的距离.
![](https://img.xkw.com/dksih/QBM/2016/3/11/1572532911251456/1572532917149696/STEM/e6e568d68d4442409511d2ff8abede5d.png)
(1)证明:A1D⊥平面A1BC;
(2)求点B到平面A1ACC1的距离.
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