1 .
中,
,点
在线段
上,下列结论正确的是()
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b375f88294490a62f58d7070be962ef5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
A.若![]() ![]() | B.若![]() ![]() |
C.若![]() ![]() | D.若![]() ![]() ![]() |
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解题方法
2 . 已知
,
.
(1)求
与
的夹角的余弦值;
(2)若
,求
值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5463fb0b7d03747aa4d680620ca81be2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80e97ecaf990a636c4648956663ff6b0.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed492f7b29166ba5c1f0023b05a439c5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3143307ad0ba4a631eac04e814993655.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/352bab087decd04caacfe66a9c0d972b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df64046e91b047037f19e4032e3b6de3.png)
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解题方法
3 . 如图,在钝角△ABC中,角A,B,C所对的边分别是a,b,c,
,过点A作与
垂直的单位向量
,将
与向量表达式
两边进行数量积的运算,即
,化简后得到的结论是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0b11d338fa58dde72c8a7402db3b97d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af5f1b06a56fc382feed28e01f1ad102.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2980a18e4d0a2a795b7983a1a1866db7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2980a18e4d0a2a795b7983a1a1866db7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0f5f98dd9945ceca75a66c207f4915a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c16be36e0f83927ac833777db5aa0fad.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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解题方法
4 . 定义:
.已知a,b,c分别为△ABC的三个内角A,B,C所对的边,若![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c23f242dc06d519ed1529c93bd1ec75e.png)
,且
,则边c的最小值为____________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0c8894e0b37af5da23a1c1bffb32017.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c23f242dc06d519ed1529c93bd1ec75e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/771df37a312dac1fb332a31a10340c29.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ff7e62312dbd1cd5b50a6dc7fdfc166.png)
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5 . 下列说法正确的是( )
A.已知![]() ![]() ![]() |
B.已知两个非零向量![]() ![]() ![]() ![]() ![]() |
C.在![]() ![]() ![]() ![]() |
D.若向量![]() ![]() ![]() ![]() ![]() |
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6 . 已知向量
,
,若
,则
( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81f4dcf415977dea53f52a85b6b82136.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/991a4493cfd34d25c6ffbadc12c27978.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6c98b14b10c0acef3c3d783984f4bb25.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ec0618ae3a4fde6d6220010af229b9a.png)
A.5 | B.2 | C.3 | D.4 |
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7 . 已知
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/652b5479cf9d1e74b30a08152733b09f.png)
____________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a5e7b5179fb9221263a20eea79f2ed1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/652b5479cf9d1e74b30a08152733b09f.png)
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解题方法
8 . 已知向量
,
,则向量
在向量
上的投影向量为____________ (用坐标表示).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/78b3515de9a26c0397039e077f272b1b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/14dfa17632f933e0468b8a7864259517.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3143307ad0ba4a631eac04e814993655.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64c5562bd4d1b54424330cb6329cd79d.png)
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9 . 我国古代的数学著作《九章算术》中的一个问题,现有一个“圆材埋壁”模型,其截面如图所示.若圆柱材料的截面圆的半径长为3,圆心为O,墙壁截面ABCD为矩形,且劣弧
的长等于半径OA长的2倍,则圆材埋在墙壁内部的阴影部分截面面积是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/16d65cecaf8a3dc2953f4109c75a981e.png)
A.![]() | B.![]() | C.![]() | D.9 |
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解题方法
10 . 在△ABC中,内角A,B,C的对边分别为a,b,c,且
.
(1)求角A的大小;
(2)若
,D是线段AC上的一点,
,
,求边c.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/28afbc29a11774be4faa4c868cd1392a.png)
(1)求角A的大小;
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0dc2e4b329bd191743c41aca4ac877b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ecb138a844ef11bb3214cff0a475c9b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/29470a095de205acb450d5a48b38be1f.png)
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