1 . 已知单位向量
,
的夹角为60°,向量
,且
,
,设向量
与
的夹角为
,则
的最大值为( ).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/05b28baf17059c56ee9ad1ae4814acd8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b04618e5b2db68f2de6ba68972c505c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97169074b37d4b914ecd271e311c0211.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95842ad442c7f6d5ec4b32939b929e63.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54eff1aaacb1ba98b5e379789f6d47a0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb80eb942aafb194fadc473776f35b1d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/05b28baf17059c56ee9ad1ae4814acd8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4d66c03d4ca06819a6ce7fc8ea6de0f0.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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2 . 已知为△ABC的内心,且
.记R、r分别为△ABC的外接圆、内切圆半径,若
,则R=____________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/249b81fa939738d06d775a4c97294394.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ecc5ff0f29dbb1816ec2a1e9aa55ee28.png)
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3 . 在△ABC中,
.则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e14176f9e46bb305075f9138eb202326.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6706fe00b4e231e62d9ecbec567d526b.png)
____________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d0f9f3d4baed5c84de69e7c05ac859e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e14176f9e46bb305075f9138eb202326.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6706fe00b4e231e62d9ecbec567d526b.png)
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2020-05-11更新
|
1139次组卷
|
3卷引用:2019年全国高中数学联赛贵州省预赛
4 . 平面上的两个向量
、
满足
,
,且
,
.若向量
,且
.则
的最大值是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef4113c492885ba7c47fe42ac792578f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b90e0f35eda1a729fed485f83da5ea9d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5038ca8098994dcc635e669b6a158d3e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1aae1bc31a8462128c1906eed27dec66.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0904a72b63d7c4fa77e7cbe9cb8448ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8825655b8b526fe207a94ca8434c82c0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/975a418253120c1e06e9c3f530c6b0c3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/668ae2d0d4265fe68e7ce3a800a9d7c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf8938257f9486c4b28768aa2cf4bb0f.png)
A.![]() | B.1 | C.2 | D.4 |
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5 . 已知从有限个平面向量构成的集合
中任取三个元素,其中总存在两个元素
,使得
.试求
中元素个数的最大值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64fa2fcefaf3d8868da0cb52877c5247.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a8e7376a9f393a3a1c7109e43b1b6c9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
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