1 . 用反证法证明命题:“一个三角形中不能有两个直角”的过程归纳以下三个步骤:
①
,这与三角形内角和为180°相矛盾,
不成立;
②所以一个三角形不能有两个直角;
③假设三角形的三个内角
,
,
中有两个直角,不妨设
;
正确顺序的序号为
①
![](https://img.xkw.com/dksih/QBM/2017/5/1/1677586164473856/1678579004547072/STEM/6099c9cb77b34dee9727cc7f2b883da7.png?resizew=140)
![](https://img.xkw.com/dksih/QBM/2017/5/1/1677586164473856/1678579004547072/STEM/add0898eebfd4fcd80ccd8076437bd1f.png?resizew=72)
![](https://img.xkw.com/dksih/QBM/2017/5/1/1677586164473856/1678579004547072/STEM/2ee94680ff604ab5a7fc921d3f439c0a.png?resizew=80)
②所以一个三角形不能有两个直角;
③假设三角形的三个内角
![](https://img.xkw.com/dksih/QBM/2017/5/1/1677586164473856/1678579004547072/STEM/08e555acbdee4f959ad68b865e4031d3.png?resizew=16)
![](https://img.xkw.com/dksih/QBM/2017/5/1/1677586164473856/1678579004547072/STEM/cd10ddb76ed347299ea35ae46177bfa0.png?resizew=16)
![](https://img.xkw.com/dksih/QBM/2017/5/1/1677586164473856/1678579004547072/STEM/8b41098b6d72429baf1fb5f33da60b4b.png?resizew=16)
![](https://img.xkw.com/dksih/QBM/2017/5/1/1677586164473856/1678579004547072/STEM/2ee94680ff604ab5a7fc921d3f439c0a.png?resizew=80)
正确顺序的序号为
A.①②③ | B.③①② | C.①③② | D.②③ |
您最近一年使用:0次