设AD,BE,CF是
的三条中线.
(1)用
和
表示
;
(2)求
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
(1)用
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f9795e7f5cb9b366776c41d8f3f43942.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be64d59ac6538a0f4d79fb825e082081.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1bd98a891fa65f2fc6688001b03185d0.png)
(2)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3556b1f44b66c4217a18b2f13492d265.png)
更新时间:2020-05-29 23:43:34
|
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解答题-问答题
|
较易
(0.85)
名校
解题方法
【推荐1】已知向量
,
.
(1)求
;
(2)若向量
,试以向量
,
为基底表示向量
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b205f7add061ae35b876fea0fc92cd1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3c1c5df2674bea51eec903294bdc1db2.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c84455ce96bb8ec069286945271a1697.png)
(2)若向量
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0679a336bb532b0a87f1f7ca6a536030.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb80eb942aafb194fadc473776f35b1d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/433b94c39737727e53468df419d8314a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bb573cc0f30d5c32cdad1510793f0e7b.png)
您最近一年使用:0次
解答题-问答题
|
较易
(0.85)
名校
【推荐2】在边长为
的正
中,设
,
.
(1)用向量
、
表示向量
,并求
的模;
(2)求
的值;
(3)求
与
的夹角的大小.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ca7d1107389675d32b56ec097464c14.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c290cdc4cf3d6b82581e68ecaf5c7f7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/939f6cf953f2c1a9f8da6717d8261a3c.png)
(1)用向量
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f9795e7f5cb9b366776c41d8f3f43942.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be64d59ac6538a0f4d79fb825e082081.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1bd98a891fa65f2fc6688001b03185d0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1bd98a891fa65f2fc6688001b03185d0.png)
(2)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/78e1c795c90d6bc673ee5f0f0548d002.png)
(3)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1bd98a891fa65f2fc6688001b03185d0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f75fc81977aee721525b4c5625f5a097.png)
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较易
(0.85)
【推荐3】在边长为1的等边三角形ABC中,设
=2
,
=3
.
(1)用向量
,
作为基底表示向量
;
(2)求
·
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0d792a2aa25763e14cc2863be3887000.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/75f90e16e18b1e88ebb1ab811d06be76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/00490134f8caa9cc28910fb1aaff85e7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f88369a480ff098461307038ceb224e2.png)
(1)用向量
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f9795e7f5cb9b366776c41d8f3f43942.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be64d59ac6538a0f4d79fb825e082081.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f75fc81977aee721525b4c5625f5a097.png)
(2)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1bd98a891fa65f2fc6688001b03185d0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f75fc81977aee721525b4c5625f5a097.png)
您最近一年使用:0次