完成下面的证明:如图,若
,CE平分
,且
,求证:
.
证明:∵CE平分
(已知)
∴
(角平分线的定义)
∵
(已知)
∴
______(______)
∴
(等量代换)
∵
(已知)
∴_______
______(______)
∴
______(两直线平行,内错角相等)
∴
(等量代换).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0fff774b4b0087a6f304ce930d359be.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f3702b5620dbee356a8e560c78d223ad.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ca2c1521d040d52acdaa1fba66ad264.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93e43ae351c7916dce6acf0fa9f048e8.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/6/30/a093f7f7-212d-4787-bbf8-c3fbb4add75c.png?resizew=175)
证明:∵CE平分
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f3702b5620dbee356a8e560c78d223ad.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e53497af8899cb299d762f1a4f46a55.png)
∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0fff774b4b0087a6f304ce930d359be.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3cc310194575262fb45352c2fbc19868.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e50ce9ef89a466df68124a1dccff5663.png)
∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fb58780ffe878f15b1200802c79cd402.png)
∴_______
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a9bfa68259d7a331be323b2038d628a.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b83764876be47a196fd5f408763738a.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93e43ae351c7916dce6acf0fa9f048e8.png)
更新时间:2023-06-25 23:26:47
|
【知识点】 根据平行线判定与性质证明
相似题推荐
解答题-作图题
|
适中
(0.65)
【推荐1】如图,
中,
,
,
,
,
.
(1)①说明
;
②小明在观察图形中感觉
似乎与
垂直,为了验证自己的猜想,他延长
与
交于点
,用量角器度量了
,测得它几乎就是
,显然测量是会出现误差的,请聪明的你用所学的几何知识说明小明的猜想是正确的.
(2)用尺规作图在原图外部取点
,使
,并请说明:点
,
,
这三个点在同一直线上.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed10df4140819d5451773a45de66201b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9060f03b9ee41d70d135b1e1a8902ce9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f2ddd49625097d0a78df7170be4f882e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2ea542c31170157c0e9b9e8b65a95437.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/934a9508c176f44bf58f88715bd98f76.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/8/19/e67461ad-74ba-4bf4-a477-944993e85cdb.png?resizew=101)
(1)①说明
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0ca0f8b08b90a3f93f9dd746506ee.png)
②小明在观察图形中感觉
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e52a8f07834cbbbe4224962672fbbb2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccaee8f228ff24e7c89879bb5b999cf2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e52a8f07834cbbbe4224962672fbbb2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccaee8f228ff24e7c89879bb5b999cf2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77282d5b97a60264cf15fb74b48e4b59.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f7a0387fc1258f31e44a10068c0ccfd0.png)
(2)用尺规作图在原图外部取点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c552b61baca3bf30a739b09ad86fddf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
您最近一年使用:0次
解答题-问答题
|
适中
(0.65)
【推荐2】如图,已知∠1+∠2=180°,∠3=∠4,试判断EF与AC的位置关系,并说明理由.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/31/6c7f0a2f-4c66-4f4c-9ecd-df88709fc5c9.png?resizew=171)
解:EF与AC的位置关系是 ,
理由:∵∠1+∠2=180°,(已知)
∠1+∠ADC=180°,( )
∴∠ADC=∠2,( )
∴AD∥ ,( )
∴∠3=∠ACB,( )
∵∠3=∠4,(已知)
∴∠ACB=∠4,( )
∴EF∥AC.( )
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/31/6c7f0a2f-4c66-4f4c-9ecd-df88709fc5c9.png?resizew=171)
解:EF与AC的位置关系是 ,
理由:∵∠1+∠2=180°,(已知)
∠1+∠ADC=180°,( )
∴∠ADC=∠2,( )
∴AD∥ ,( )
∴∠3=∠ACB,( )
∵∠3=∠4,(已知)
∴∠ACB=∠4,( )
∴EF∥AC.( )
您最近一年使用:0次