题目内容
已知
,给出下列说法:①若
与
的夹角为锐角,则
;②当且仅当
时,
与
互相垂直;③
与
不可能是方向相反的两个向量;④若
,则
.其中正确的序号是
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823200034366247.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/201408232000341481218.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823200034163300.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823200034179321.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823200034195532.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823200034210521.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823200034163300.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823200034179321.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823200034163300.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823200034179321.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823200034288479.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823200034319458.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823200034335247.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823200034366247.png)
A.①②③ | B.①②③④ | C.②④ | D.②③ |
A
由条件知
若
与
的夹角为锐角,则
。①正确;
。②正确;
与
是方向相反的两个向量,则![](http://thumb.1010pic.com/pic2/upload/papers/20140823/201408232000348501516.png)
与
矛盾,③正确;
④错误;故选A
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823200034382817.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823200034163300.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823200034179321.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823200034553968.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/201408232000345851126.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823200034163300.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823200034179321.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/201408232000348501516.png)
与
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823200034865439.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140823/20140823200034897914.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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题目内容
A.①②③ | B.①②③④ | C.②④ | D.②③ |