题目
题型:不详难度:来源:
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012814-10715.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012814-70366.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012814-51169.png)
A.一定为锐角三角形 | B.一定为钝角三角形 |
C.一定为直角三角形 | D.可以为任意三角形 |
答案
解析
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012814-83569.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012815-20146.png)
即
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012815-86604.png)
因为上式对任意的
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012814-10715.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012815-69974.png)
即
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012815-85229.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012816-25298.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012816-74946.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012816-60596.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012816-50043.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012817-98542.png)
因为在
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012814-51169.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012817-33795.png)
所以
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012817-17707.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012817-11093.png)
故选
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012818-14899.png)
【考点】三角形形状的判断.
核心考点
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012800-38027.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012801-63680.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012801-49821.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012801-65597.png)
(1)若
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012801-48262.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012801-98123.png)
(2)若
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012801-65583.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012801-49104.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012801-79215.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012755-86350.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012755-68982.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012755-34746.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012750-12553.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012750-57929.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012750-79827.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012750-97111.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012751-83637.png)
已知复数
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012740-11987.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012740-26768.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012741-75682.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012741-27273.png)
(1)若
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012741-83211.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012741-49536.png)
(2)若
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012741-24600.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012741-89045.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012741-32151.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012723-68627.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012723-51775.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012724-91543.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012724-96021.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012724-43424.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012724-98431.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012724-90097.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012725-10187.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012725-62934.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012725-15582.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012725-10318.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012726-89554.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012726-75225.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012726-94302.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012726-91574.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012726-94302.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012726-89554.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012727-15257.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012726-89554.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105012727-81205.png)
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