题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140142-44512.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140142-60738.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140142-10773.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140142-58192.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140142-15458.png)
(1)求证:
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140143-34780.png)
(2)求证:
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140143-65251.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140143-72076.png)
(3)求三棱锥
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140143-65372.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140144-94218.png)
![]() |
答案
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140144-93631.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140144-30530.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140144-83720.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140145-38743.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140145-64734.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140145-51917.png)
又
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140145-47482.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140145-46670.png)
∵
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140146-13930.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140146-58404.png)
而
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140146-34681.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140146-42686.png)
(2)设
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140146-53464.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140147-48971.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140147-44024.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140147-82274.png)
∵直三棱柱
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140142-44512.png)
∴四边形
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140148-42460.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140147-44024.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140147-48971.png)
又
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140142-58192.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140142-15458.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140148-59079.png)
而
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140149-57546.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140149-42390.png)
(3)连结
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140149-93592.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140149-18284.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140149-43164.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140149-51784.png)
在
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140150-23742.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140150-67944.png)
又∵直三棱柱
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140142-44512.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140150-17036.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140150-85819.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140150-33316.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140149-43164.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140150-11254.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140151-59472.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140151-26948.png)
又
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140151-31784.png)
∴
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140151-43193.png)
解析
核心考点
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140129-48341.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140129-28263.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140130-33426.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140130-27049.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140130-33670.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140130-90712.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140130-71986.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140129-28263.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140130-33426.png)
A.![]() | B.![]() |
C.![]() | D.2![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140130-85555.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140124-59726.png)
A.以下四个图形都是正确的 | B.只有(1)(4)是正确的 |
C.只有(1)(2)(4)是正确的 | D.只有(2)(3)是正确的 |
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140118-35372.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140111-71202.png)
A.![]() | B.![]() | C.![]() | D.![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140106-81936.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140107-62012.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191021/20191021140107-20921.png)
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