如图,在
中,点E在边AD上,以C为圆心,AE长为半径画弧,交边BC于点F,连接BE,DF,求证:BE=DF.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5138a9f70d5e8b0580e30fef6eb7baef.png)
![](https://img.xkw.com/dksih/QBM/2020/4/28/2451229113933824/2453569591492608/STEM/1b847db5f169410aaf5d06625f48972e.png?resizew=138)
更新时间:2020-05-01 22:23:01
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【知识点】 用SAS直接证明三角形全等(SAS)解读
相似题推荐
解答题-作图题
|
适中
(0.65)
名校
【推荐1】华师版九年级上册教材第103页利用作斜边中点的方法,探究了:“在直角三角形中,
锐角所对的直角边与斜边的数量关系.”我们还能用其他的方法证明这个结论吗?
下面是小明的探究过程,请根据他的思路完成以下作图和填空:
已知:如图,在
中,
,
,求证:
.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/25/6db3d149-66de-495c-b000-1181c8a2cc87.png?resizew=195)
(1)尺规作图:作
的角平分线交
于点
,在
上取一点
,使得
,连接
(保留作图痕迹,不写作法);
(2)证明:∵
,
,
∴
.
∵
平分
,
∴
①
.
在
与
中,
,∴
.
∴ ②
,∴
.
又∵
,∴
③ ,
∴点
是
的中点,∴ ④
.
∵
,∴
.
利用小明的探究过程,我们可以得到的结论:在直角三角形中,如果一个锐角等于
,那么 ⑤
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6b86c22b670a8e9f3896f9e8883fbbb.png)
下面是小明的探究过程,请根据他的思路完成以下作图和填空:
已知:如图,在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/90b40c2b0ab8e1cfe5112d428b4b829f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed10df4140819d5451773a45de66201b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aabecf66d94e4094f9cc46fd8ee050f1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ebe44ff9f829f6c034682572ad00e366.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/25/6db3d149-66de-495c-b000-1181c8a2cc87.png?resizew=195)
(1)尺规作图:作
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d39b8d91afc34e4a9b0fdbb6bafb9087.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7dea2ae9d515f9ab351ad72306b776ee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df1ac3ab8d3ce5e61fd2f89761f80976.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
(2)证明:∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed10df4140819d5451773a45de66201b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aabecf66d94e4094f9cc46fd8ee050f1.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e075468e7fb0bf30229aec01a7205977.png)
∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d39b8d91afc34e4a9b0fdbb6bafb9087.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6523615f59be6afb9c85a8fd13986189.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cfe405c5b31ac1a299dcf9ebf1c48ec8.png)
在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73636989e83905f8800a865c2b608c43.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b96715995549e5e48494101570bb3bb8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d64c144df5d0ac6cf6b9daeb7eeb18a2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8448a7c2cccf35c35ed99e3796ff87ee.png)
∴ ②
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/078d53df2f508ed2680e9ae1065d054d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/32c38dfd14dde969702dff97ef2270f9.png)
又∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/403f100f138c2956ecc1265392a194aa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e2152ac6e0a9abe7378ca935fa593e9.png)
∴点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/494dce4637098c05c250422c917ba7fc.png)
∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df1ac3ab8d3ce5e61fd2f89761f80976.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ebe44ff9f829f6c034682572ad00e366.png)
利用小明的探究过程,我们可以得到的结论:在直角三角形中,如果一个锐角等于
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6b86c22b670a8e9f3896f9e8883fbbb.png)
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解答题-作图题
|
适中
(0.65)
【推荐2】[问题提出]我们知道:同弧或等弧所对的圆周角都相等,且等于这条弧所对的圆心角的一半,那么在一个圆内同一条弦所对的圆周角与圆心角之间又有什么关系呢?
[初步思考]
(1)如图1,
是
的弦,
,点
、
分别是优弧
和劣弧
上的点,则
______
,
_____
;
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/9/86192350-c6db-4d44-847c-17a161c571c3.png?resizew=126)
(2)如图2,
是
的弦,圆心角
,点
是
上不与
、
重合的一点,求弦
所对的圆周角
的度数为_______________;(用m的代数式表示)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/9/ae180911-fda5-4bec-a002-1eed488cdb77.png?resizew=123)
[问题解决]
(3)如图3,已知线段
,点
在
所在直线的上方,且
,用尺规作图的方法作出满足条件的点C所组成的图形(① 直尺为无刻度直尺;② 不写作法,保留作图痕迹);
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/9/2162c6ea-191a-43a8-9b8c-c89ab1c6be38.png?resizew=106)
[实际应用]
(4)如图4,在边长为6的等边三角形
中,点
、
分别是边
、
上的动点,连接
、
,交于点
,若始终保持
,当点E从点A运动到点C时,点P运动的路径长是__________________.
[初步思考]
(1)如图1,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/950a96f120b449d9cf5c1709867c3d2d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2708fa6298e52f617383efc175b71ddc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b9cb8e6ff801523b0304576cd69fd2d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/afc95b1289f7f443d3137ed960c8b406.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83873a9d782f2588c5eedbfe73f9bc2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c134bff1d7144fe568d492660c54c22a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83873a9d782f2588c5eedbfe73f9bc2f.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/9/86192350-c6db-4d44-847c-17a161c571c3.png?resizew=126)
(2)如图2,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a9e67f55689808b2eab465a7b577df4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb686e4f5e3938575bc547e849d5513f.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/9/ae180911-fda5-4bec-a002-1eed488cdb77.png?resizew=123)
[问题解决]
(3)如图3,已知线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/86a0946888ae70f1d37116c2d3867720.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/9/2162c6ea-191a-43a8-9b8c-c89ab1c6be38.png?resizew=106)
[实际应用]
(4)如图4,在边长为6的等边三角形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6aa2b5e09f8ec785c59900a529390a02.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d8ce1475f537b4ad21775bfaa16daa0c.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/9/0ddc3690-77cd-4308-8482-f06b2f2fb6e7.png?resizew=126)
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