解答题-证明题 适中0.65 引用3 组卷678
如图所示的多面体,它的正视图为直角三角形,侧视图为矩形,俯视图为直角梯形(尺寸如图所示)
(1)求证:AE//平面DCF;
(2)当AB的长为
,
时,求二面角A—EF—C的大小.
![](https://img.xkw.com/dksih/QBM/2011/3/29/1570085586083840/1570085591171072/STEM/cdd4a667e2f34d0babb77c858d577531.png?resizew=239)
![](https://img.xkw.com/dksih/QBM/2011/3/29/1570085586083840/1570085591171072/STEM/b33953b57e1449a5af4ec29f4c3b348f.png?resizew=304)
(1)求证:AE//平面DCF;
(2)当AB的长为
![](https://img.xkw.com/dksih/QBM/2011/3/29/1570085586083840/1570085591171072/STEM/cdd4a667e2f34d0babb77c858d577531.png?resizew=239)
![](https://img.xkw.com/dksih/QBM/2011/3/29/1570085586083840/1570085591171072/STEM/b33953b57e1449a5af4ec29f4c3b348f.png?resizew=304)
2010·辽宁·一模
类题推荐
组卷网是一个信息分享及获取的平台,不能确保所有知识产权权属清晰,如您发现相关试题侵犯您的合法权益,请联系组卷网
组卷网是一个信息分享及获取的平台,不能确保所有知识产权权属清晰,如您发现相关试题侵犯您的合法权益,请联系组卷网