题目
题型:不详难度:来源:
①对任意两向量a,b,均有:|a|-|b|<|a|+|b|;
②对任意两向量a,b,a-b与b-a是相反向量;
③在△ABC中,
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-39728.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-39496.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-97745.png)
④在四边形ABCD中,(
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-39728.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-39496.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-39504.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014843-62684.png)
⑤在△ABC中,
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-39728.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-97745.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-39496.png)
A.①②③ | B.②④⑤ |
C.②③④ | D.②③ |
答案
解析
②真命题.∵(a-b)+(b-a)=a+(-b)+b+(-a)=a+(-a)+b+(-b)=(a-a)+(b-b)=0,
∴a-b与b-a是相反向量.
③真命题.∵
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-39728.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-39496.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-97745.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-97745.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-97745.png)
∴命题成立.
④假命题.∵
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-39728.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-39496.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-97745.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-39504.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014843-62684.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014843-47307.png)
∴(
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-39728.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-39496.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-39504.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014843-62684.png)
=
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-97745.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014843-47307.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-97745.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-97745.png)
∴该命题不成立.
⑤假命题.∵
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-39728.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-97745.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-39728.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014843-47307.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014843-92801.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014842-39496.png)
∴该命题不成立.
核心考点
试题【下列命题中是真命题的是( )①对任意两向量a,b,均有:|a|-|b|<|a|+|b|;②对任意两向量a,b,a-b与b-a是相反向量;③在△ABC中,】;主要考察你对平面向量应用举例等知识点的理解。[详细]
举一反三
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014834-43982.jpg)
A.![]() ![]() |
B.![]() ![]() |
C.![]() ![]() |
D.![]() ![]() ![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014827-83364.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014827-18459.png)
A.λ+μ=2 | B.λ-μ=1 |
C.λμ=-1 | D.λμ=1 |
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014821-88284.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014821-35918.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014821-29239.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014821-89382.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014822-48549.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014822-96341.png)
A.2 | B.![]() | C.3 | D.![]() |
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014816-25654.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014816-60982.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014816-84552.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014816-25654.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014816-60982.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014816-25654.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014816-84552.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014816-25654.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014816-60982.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014816-84552.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014817-21149.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014816-84552.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014816-25654.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014816-60982.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014817-16219.jpg)
A.4 | B.5 | C.6 | D.8 |
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014810-64865.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014810-79105.png)
![](http://img.shitiku.com.cn/uploads/allimg/20191105/20191105014810-57989.png)
A.0<t<![]() | B.0<t<![]() | C.0<t<![]() | D.0<t<![]() |
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