题目
题型:不详难度:来源:
DE把该三角形折成直二面角,此时斜边AC被折成折线ADC,则∠ADC等于
( )
A.150° | B.135° | C.120° | D.100° |
答案
解析
![]() | |||
![]() | |||
在等腰直角三角形ABC中,∠B=90°,AC,BC的中点分别是D,E,所以
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075320-19213.png)
在折成直二面角图形中
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075320-31854.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075321-29052.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075321-26718.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075321-59935.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075321-78964.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075322-82814.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075322-76625.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075322-57250.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075322-70584.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075323-69801.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075323-54343.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075323-50205.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075323-15892.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075323-29381.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075324-31891.png)
核心考点
试题【8、已知等腰直角三角形ABC中,∠B=90°,AC,BC的中点分别是D,E,DE把该三角形折成直二面角,此时斜边AC被折成折线ADC,则∠ADC等于 (】;主要考察你对线线角等知识点的理解。[详细]
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075311-37286.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075311-60677.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075311-32578.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075312-74510.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075312-95581.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075312-76431.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075312-12184.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075312-22482.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075311-60677.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075312-41001.gif)
求证:(1)平面
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075312-99806.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075312-84802.gif)
(2)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075312-14425.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075311-60677.gif)
(3)平面
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075313-88603.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075313-91152.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075313-54268.gif)
(理科)如图,四边形
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075300-29592.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075300-99024.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075300-29592.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075301-19949.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075300-99024.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075301-68838.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075301-96351.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075301-11233.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075302-39980.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075302-15618.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075302-39220.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075302-83484.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075303-22509.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075303-92931.gif)
(Ⅱ)求平面
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075303-80964.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075303-10083.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075237-77669.jpg)
如图,四边形ABCD为正方形,QA⊥平面ABCD,PD∥QA,QA=AB=
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075237-39351.gif)
(I)证明:PQ⊥平面DCQ;
(II)求棱锥Q—ABCD的的体积与棱锥P—DCQ的体积的比值.
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075233-18211.gif)
(1)求证:PA⊥平面ABCD;(2)求异面直线
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075233-62546.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075234-36698.jpg)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075222-84808.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075222-46151.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075222-58854.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075223-53206.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075224-73242.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075224-45745.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075224-89718.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075224-84631.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075225-18704.png)
A.![]() | B.![]() | C.![]() | D.![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191022/20191022075227-22508.png)
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