如图,△ABC是等边三角形,D为BA的中点,DE⊥AC,垂足为点E,EF//AB,AE=2,下列结论错误的是( )
![](https://img.xkw.com/dksih/QBM/2022/1/17/2896560440442880/2928514744836096/STEM/08a82cfa-03ac-433a-97be-1d55ac440c4b.png?resizew=138)
![](https://img.xkw.com/dksih/QBM/2022/1/17/2896560440442880/2928514744836096/STEM/08a82cfa-03ac-433a-97be-1d55ac440c4b.png?resizew=138)
A.∠ADE=30° | B.BD=4 |
C.△EFC的周长为18 | D.△ABC的周长为21 |
更新时间:2022-03-03 23:01:24
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【推荐1】如图,在△ABC中,∠C=90°,∠B=30°,以A为圆心,任意长为半径画弧分别交AB、AC于点M和N,再分别以M、N为圆心,大于
MN的长为半径画弧,两弧交于点P,连结AP并延长交BC于点D,则下列说法中正确的个数是( )
①作出AD的依据是SAS;
②∠ADC=60°
③点D在AB的中垂线上;
④S△DAC:S△ABD=1:2.
![](https://img.xkw.com/dksih/QBM/2019/2/28/2150478037393408/2153218975326208/STEM/66446c72-d34b-4372-bfae-50e723a60017.png?resizew=224)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8eff998d034284391ca064755fa6bf1b.png)
①作出AD的依据是SAS;
②∠ADC=60°
③点D在AB的中垂线上;
④S△DAC:S△ABD=1:2.
![](https://img.xkw.com/dksih/QBM/2019/2/28/2150478037393408/2153218975326208/STEM/66446c72-d34b-4372-bfae-50e723a60017.png?resizew=224)
A.1![]() | B.2![]() | C.3![]() | D.4 |
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【推荐2】如图,在
中,
,
,将
绕点C顺时针旋转
得到
,点
与点B是对应点,若点
恰好落在
边上,则点A到直线
的距离等于( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd967903ed5a6f640a5b801ec8be0070.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca51953bbd064b0718c5eaeb71f235f3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f3018c687427b6257767eda4a8c6612.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be6a6301878fed2a01413020b27310a5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b185184dc2dc3894a0313fd13f26a59.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3953cec61ac602ce5eb59b7912352179.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3953cec61ac602ce5eb59b7912352179.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6eb97aff0960e2640314888a38e7169c.png)
A.1 | B.![]() | C.![]() | D.![]() |
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【推荐1】如图,过边长为1的等边△
的边
上一点
,作
于点
,
为
延长线上一点,当
时,连接
交
边于点
,则
的长为( )
![](https://img.xkw.com/dksih/QBM/2019/10/28/2321600720568320/2324758110404608/STEM/45d3efe3c3844de0995d3cf8a315a18d.png?resizew=169)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5bc56fdf70e65bd88980c64af96b83da.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dfa93b36319dccba34cd63404d719018.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7a5f1641947153c80b987320885a2b57.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://img.xkw.com/dksih/QBM/2019/10/28/2321600720568320/2324758110404608/STEM/45d3efe3c3844de0995d3cf8a315a18d.png?resizew=169)
A.1 | B.![]() | C.![]() | D.![]() |
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【推荐2】如图,将一块
角的直角三角板
(
)绕直角顶点C逆时针旋转到
的位置,此时点
刚好在
上,若
,则点B与点
距离为( )
![](https://img.xkw.com/dksih/QBM/2023/1/2/3144124341362688/3157062616326144/STEM/b4e8567a44da4f6b9ceedc5ce7bfaff2.png?resizew=132)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6b86c22b670a8e9f3896f9e8883fbbb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9cf468f5132e14ee1d8cc766808b11af.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5d4e7eaee73a42ad47a4adf5261ee761.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/400d32d1f7dbeb0f8ca3f94288716cf6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac7856b843caf384fca612ce663f21c9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1cf1abe5cf81aae9ee2e428da471cb0f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d70dc2c20619a4fc12a0cfda59af5b69.png)
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![](https://img.xkw.com/dksih/QBM/2023/1/2/3144124341362688/3157062616326144/STEM/b4e8567a44da4f6b9ceedc5ce7bfaff2.png?resizew=132)
A.6 | B.![]() | C.![]() | D.![]() |
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解题方法
【推荐3】已知等边三角形ABC.如图,
(1)分别以点A,B为圆心,大于的
AB长为半径作弧,两弧相交于M,N两点;
(2)作直线MN交AB于点D;
(2)分别以点A,C为圆心,大于
AC的长为半径作弧,两弧相交于H,L两点;
(3)作直线HL交AC于点E;
(4)直线MN与直线HL相交于点O;
(5)连接OA,OB,OC.
根据以上作图过程及所作图形,下列结论:①OB=2OE;②AB=2OA;③OA=OB=OC;④∠DOE=120°,正确的是( )
![](https://img.xkw.com/dksih/QBM/2020/6/20/2488491326734336/2492463358238721/STEM/5a959bccd1774f93937f2d9856cd5ead.png?resizew=224)
(1)分别以点A,B为圆心,大于的
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
(2)作直线MN交AB于点D;
(2)分别以点A,C为圆心,大于
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
(3)作直线HL交AC于点E;
(4)直线MN与直线HL相交于点O;
(5)连接OA,OB,OC.
根据以上作图过程及所作图形,下列结论:①OB=2OE;②AB=2OA;③OA=OB=OC;④∠DOE=120°,正确的是( )
![](https://img.xkw.com/dksih/QBM/2020/6/20/2488491326734336/2492463358238721/STEM/5a959bccd1774f93937f2d9856cd5ead.png?resizew=224)
A.①②③④ | B.①③④ | C.①②③ | D.③④ |
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