如图,在
中,
,D为
上一点,且
,过D作
,连接
,且
.
(1)求证:
;
(2)若
,
,求
的长.
![](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/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7de966c316db1013defc56372fcf814e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bffd657e48b15b9b54a55817e2c26b22.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/40b3e9a99b5b8258baab51f66d1a48ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d4e92f48e9bfe12d145f7d2a2f0360d0.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/7/27/4f37d74b-6767-43b7-be6e-0fe3ce8448c7.png?resizew=175)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d1fc8b2e9ba57d7b586cbd6121127e59.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61e7917dd4f9ef287f39003509fcb867.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/833cfda415649b832cc136caed392753.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
更新时间:2023-07-26 09:09:39
|
相似题推荐
解答题-计算题
|
适中
(0.65)
【推荐1】计算或求式中
的值.
(1)计算:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/07eb3a303bae1f8c2645a0adeeafa9a3.png)
(2)求式中
的值:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
(1)计算:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/07eb3a303bae1f8c2645a0adeeafa9a3.png)
(2)求式中
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3b05c13ea44b46ffd8469d81dfa653a7.png)
您最近一年使用:0次
解答题-证明题
|
适中
(0.65)
名校
【推荐1】小明在学习完“等腰三角形底边上的高线、中线及顶角平分线重合”,继续探索,他猜想“如果三角形的一条角平分线是这个角对边上的中线,那么这个三角形是等腰三角形”并进行证明.
已知:如图,在△ABC中,AD平分∠BAC,D为BC中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/17/7aa94050-edb6-439a-be8b-18a63c22e03c.png?resizew=138)
求证:△ABC是等腰三角形.
小明的证法:如图,过点D作DE⊥AB,DF⊥AC,垂足为点E、F.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/17/54faed5a-55fb-45aa-95c7-12e79ca53393.png?resizew=133)
∵DE⊥AB,DF⊥AC,
∴∠BED=∠CFD=90°.
∵ ① ,DE⊥AB,DF⊥AC,
∴ DE=DF.
∵D为BC中点,
∴BD=CD.
在Rt△BED和Rt△CFD中,∠BED=∠CFD=90°,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5eccdde84f1e05f4701aa6c878d1fe41.png)
∴Rt△BED≌Rt△CFD(HL).
∴ ② .
∴AB=AC.
∴△ABC是等腰三角形.
请把小明的证法补充完整,并用不同的方法完成证明.
已知:如图,在△ABC中,AD平分∠BAC,D为BC中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/17/7aa94050-edb6-439a-be8b-18a63c22e03c.png?resizew=138)
求证:△ABC是等腰三角形.
小明的证法:如图,过点D作DE⊥AB,DF⊥AC,垂足为点E、F.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/17/54faed5a-55fb-45aa-95c7-12e79ca53393.png?resizew=133)
∵DE⊥AB,DF⊥AC,
∴∠BED=∠CFD=90°.
∵ ① ,DE⊥AB,DF⊥AC,
∴ DE=DF.
∵D为BC中点,
∴BD=CD.
在Rt△BED和Rt△CFD中,∠BED=∠CFD=90°,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5eccdde84f1e05f4701aa6c878d1fe41.png)
∴Rt△BED≌Rt△CFD(HL).
∴ ② .
∴AB=AC.
∴△ABC是等腰三角形.
请把小明的证法补充完整,并用不同的方法完成证明.
您最近一年使用:0次