已知点D,E,F分别为△ABC的边BC,CA,AB的中点,且
=
,
=
,给出下列命题:
①
=![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
-
; ②
=
+![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
;
③
=-![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
+![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
; ④
+
+
=0.
其中正确命题的序号为________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cbce33d610dc616d4b1076194745ad9c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb80eb942aafb194fadc473776f35b1d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7b624db1eb415063a69c84f6dc07de05.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/433b94c39737727e53468df419d8314a.png)
①
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5fe80687551fd69359120ebdd4a45fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.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/4616054315c593433845f296222bb637.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb80eb942aafb194fadc473776f35b1d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/433b94c39737727e53468df419d8314a.png)
③
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d229fb1c526050f42d65572510b2fef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb80eb942aafb194fadc473776f35b1d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/433b94c39737727e53468df419d8314a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5fe80687551fd69359120ebdd4a45fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4616054315c593433845f296222bb637.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d229fb1c526050f42d65572510b2fef.png)
其中正确命题的序号为
2019高三·全国·专题练习 查看更多[2]
(已下线)2019高考热点题型和提分秘籍 【理数】专题18 平面向量的概念及其线性运算( 题型专练)(已下线)2019高考热点题型和提分秘籍 【文数】专题18 平面向量的概念及其线性运算( 题型专练)
更新时间:2018-12-15 20:22:58
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【推荐1】如图所示,平行四边形
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,
,
是
中点,那么向量
与
所成角的余弦值等于______ .
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您最近一年使用:0次
填空题-单空题
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【推荐2】已知
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_________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
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解题方法
【推荐2】正五角星是一个与黄金分割有着密切联系的优美集合图形,在如图所示的正五角星中,A、B、C、D、E是正五边形的五个顶点,且
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______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7131d592e355f7745107cbf08a26c314.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/27f79ed6b24371cd7c7f07b72812e702.png)
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![](https://img.xkw.com/dksih/QBM/2022/4/24/2964818012635136/2965849752166400/STEM/f858d6a7-8db1-4122-bee4-0529c5702035.png?resizew=228)
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