1 . 设
为实数,若向量
.
(1)若
与
垂直,求
的值;
(2)当
为何值时,
三点共线.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0192561f4ead4f95871b50f2c2a8d5b7.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93c0f0a6242f7b1313fd149d797ef62e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef8337706c550bc095d7a2bd872221a1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
(2)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0a532e15e232cb4b99a8d4d07c89575.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24e0c10fb103930eabd5fa18e8f9bb06.png)
您最近一年使用:0次
2 . 设
为
的内角,向量
,向量
,则( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf6fa747c6f517302ce91c8e7a846fd8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/98317e669d2483e4898c2e171a8106d4.png)
A.对任意![]() | B.存在![]() ![]() |
C.存在![]() ![]() | D.对任意![]() ![]() |
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