如图,
是
的中点,
,
,
,且
平分
.求证:
是等边三角形.补全下面的证明过程及理由.
证明:∵
平分
(已知),
∴
___________(___________).
∵
(已知),
∴
__________°.
∵
(已知),
∴
__________(___________),
∴
.
又∵
(已知),
∴
是等边三角形(____________).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8d33367290ac86e10c2200df76f294b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acd122d829e5a1e313c6cc867fc4ce61.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a2612c3ed33135b60b5a08c173c9f84.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d004d2d115b477ade6af7ddb93db0df8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95efaa2bb4dce0f63f4a23e0f29c5aa0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2657e02314469ad2b13d31dce41b4343.png)
证明:∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d004d2d115b477ade6af7ddb93db0df8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95efaa2bb4dce0f63f4a23e0f29c5aa0.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b4783ac8001d2dd147c629e893b313a.png)
∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acd122d829e5a1e313c6cc867fc4ce61.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2cec152092c31e3699e5f9dcdbe3c791.png)
∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a2612c3ed33135b60b5a08c173c9f84.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1ec7bd34c390cb2c5c03fdbdc0067947.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5d875f0d9448d025bb6dfad47dd55fad.png)
又∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8d33367290ac86e10c2200df76f294b9.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bbfa1a2af7e38d33634c462300df381f.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/1/95014f1e-abaf-43f1-9120-35901b0ef5a7.png?resizew=210)
17-18七年级下·上海虹口·期末 查看更多[11]
上海市虹口区2017-2018学年七年级下学期期末数学试题(已下线)第12讲 等边三角形(核心考点讲与练)-2021-2022学年七年级数学下学期考试满分全攻略(沪教版)贵州省铜仁市石阡县2022-2023学年八年级上学期期中数学试题(已下线)14.7 等边三角形(分层练习)-2022-2023学年七年级数学下册同步精品课堂(沪教版)(已下线)专题13.17 等边三角形(分层练习)(提升练)-2023-2024学年八年级数学上册基础知识专项突破讲与练(人教版)(已下线)专题2.17 等边三角形的轴对称性(分层练习)(提升练)-2023-2024学年八年级数学上册基础知识专项突破讲与练(苏科版)(已下线)专题13.4 等边三角形的性质与判定【十大题型】-2023-2024学年八年级数学上册举一反三系列(华东师大版)(已下线)专题13.3 等边三角形的性质与判定【十大题型】-2023-2024学年八年级数学上册举一反三系列(人教版)(已下线)专题2.3 等边三角形的性质与判定【十大题型】-2023-2024学年八年级数学上册举一反三系列(浙教版)(已下线)专题2.3 等边三角形的性质与判定【十大题型】-2023-2024学年八年级数学上册举一反三系列(苏科版)(已下线)专题15.3 等边三角形的性质与判定【十大题型】-2023-2024学年八年级数学上册举一反三系列(沪科版)
更新时间:2023-02-24 14:01:01
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解答题-问答题
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较易
(0.85)
【推荐1】如图,已知
,
,
、
分别是垂足,且
平分
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/9/2/9b4294b6-c1d8-41c9-8e72-00228d4f333b.png?resizew=193)
(1)
与
相等吗?请说明理由.
(2)求
的度数.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b5f215a42c4b7078d8d65923eb9980e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c8c13ab7f17263c4e6163d960f1c5060.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7cbce11aa19b8bd2bf6ee5a834e005de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20494d4eb6bc7147dce884c4c8213a5f.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/9/2/9b4294b6-c1d8-41c9-8e72-00228d4f333b.png?resizew=193)
(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b871a762469393cdd22f15aa49ebb8f9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/13a2e6494cf8d2dff0746a9bb72cef43.png)
(2)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e37b078d02601f76f0f8320b410809f.png)
您最近一年使用:0次
解答题-作图题
|
较易
(0.85)
【推荐2】补全下面的解答过程.
如图,
,点E,F在直线CD下方,连接BE,DE,BF,DF,BF与CD交于点G.已知BE平分∠ABF,DE平分∠CDF,
,探究∠E与∠CDF的数量关系.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/20/7d48ec64-9274-4818-a92d-c3e27de00998.png?resizew=225)
解:∵
,
∴∠ABF=______( ),
∵BE平分∠ABF,
∴
,(角平分线的定义),
∵
,
∴∠EBF=______(等量代换),
∴
( ),
∴_____=∠EDF( ),
∵DE平分∠CDF,
∴∠CDF=2∠EDF(角平分线的定义)
∴______.
如图,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0fff774b4b0087a6f304ce930d359be.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/611f35f8c26cc945a87ecff0f4422b6a.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/20/7d48ec64-9274-4818-a92d-c3e27de00998.png?resizew=225)
解:∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0fff774b4b0087a6f304ce930d359be.png)
∴∠ABF=______( ),
∵BE平分∠ABF,
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/effdd72ae56a885b4a4bae70090fd613.png)
∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/611f35f8c26cc945a87ecff0f4422b6a.png)
∴∠EBF=______(等量代换),
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ada55c12a53a4c469e052445547bed96.png)
∴_____=∠EDF( ),
∵DE平分∠CDF,
∴∠CDF=2∠EDF(角平分线的定义)
∴______.
您最近一年使用:0次
解答题-作图题
|
较易
(0.85)
【推荐1】如图,在□ABCD中,∠B=60°.
(1)作∠A的角平分线与边BC交于点E(用尺规作图,保留作图痕迹,不要求写作法);
(2)求证:△ABE是等边三角形.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/29/87713408-1f92-4715-a4ce-2c9496fd7cb7.png?resizew=219)
(1)作∠A的角平分线与边BC交于点E(用尺规作图,保留作图痕迹,不要求写作法);
(2)求证:△ABE是等边三角形.
您最近一年使用:0次
解答题-证明题
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较易
(0.85)
名校
【推荐2】如图,在
中,
是
边的中线,
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沿
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的形状并加以证明.
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/661ff55b5ebbadfb600989af3cfce2fd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
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![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/13/0f43ba82-360f-4a83-84dd-0f36e8933a80.png?resizew=151)
您最近一年使用:0次