数学概念:如图①,在△ABC中,D为∠ABC的对边AC上一点(点D不与点A、C重合),连接BD.若∠ADB和∠CDB这两个角中至少存在1个与∠ABC相等,则称BD为△ABC中∠ABC的等角分割线.
![](https://img.xkw.com/dksih/QBM/2021/10/29/2839691527626752/2914084275544064/STEM/e658bece-a4a4-44ae-be2f-fcb31a9e1f89.png?resizew=268)
(1)概念理解:如图②,在Rt△ABC中,∠C=90°,∠B=60°.分别画出∠B和∠C的等角分割线BD、CE.(画图工具不限,并做出适当的标注)
(2)知识运用:在△ABC中,∠A=50°,∠ACB=70°.已知∠ABC、∠ACB的等角分割线BD、CE相交于点O,求∠BOC的度数.
(3)深入思考:下列关于“等角分割线”的结论:
①钝角三角形中的钝角有2条等角分割线;
②三个角都不相等的三角形中,最小的角没有等角分割线;
③三角形的高、角平分线可能是该三角形中的等角分割线;
④任意一个三角形中最少有1条等角分割线,最多有3条等角分割线.
其中所有正确结论的序号是 .
![](https://img.xkw.com/dksih/QBM/2021/10/29/2839691527626752/2914084275544064/STEM/e658bece-a4a4-44ae-be2f-fcb31a9e1f89.png?resizew=268)
(1)概念理解:如图②,在Rt△ABC中,∠C=90°,∠B=60°.分别画出∠B和∠C的等角分割线BD、CE.(画图工具不限,并做出适当的标注)
(2)知识运用:在△ABC中,∠A=50°,∠ACB=70°.已知∠ABC、∠ACB的等角分割线BD、CE相交于点O,求∠BOC的度数.
(3)深入思考:下列关于“等角分割线”的结论:
①钝角三角形中的钝角有2条等角分割线;
②三个角都不相等的三角形中,最小的角没有等角分割线;
③三角形的高、角平分线可能是该三角形中的等角分割线;
④任意一个三角形中最少有1条等角分割线,最多有3条等角分割线.
其中所有正确结论的序号是 .
更新时间:2022-02-11 13:42:32
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相似题推荐
解答题-证明题
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名校
【推荐1】如图,
交
于点D,
,
.
![](https://img.xkw.com/dksih/QBM/2021/2/18/2660675682459648/2680698062585856/STEM/ef4863f0-624f-4737-9d64-c654f4c68027.png?resizew=268)
(1)求证:
;
(2)若
,求
的度数.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3fa96529beb1b15355b849cef599a120.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e735a28578ba191da6d4f3b0f8e8729.png)
![](https://img.xkw.com/dksih/QBM/2021/2/18/2660675682459648/2680698062585856/STEM/ef4863f0-624f-4737-9d64-c654f4c68027.png?resizew=268)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a668fcb9a29eebda06220828d3b0877d.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68e744f480e11f588570c5d6738799f5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7d19f963f7c803bcfcbb265ec6d4304.png)
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名校
【推荐2】
中,
是
的角平分线,
是
的高.
,
,求
的度数;
(2)如图2,
,由
的计算结果,你能发现
与
的数量关系吗?写出这个关系式,并加以证明;
(3)如图3,
,
延长
到点
,
和
的角平分线交于点
、请直接写出
的度数______.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.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/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/640e9e7c56e8eeda044fb55396088816.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/998329f9cdb86f5d60d7d5d70fc3781e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/57e7106619c08f2bcc1d21f846e8a0de.png)
(2)如图2,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2e9019487563439986e1106739c4845.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9bf6c84731e5e1bd335ecfc2d36c3d81.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63b43490ca09467a4c8cd8cfe91c94e4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2bc9681a6731e838b62bb7481df2a74.png)
(3)如图3,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56d3c9ce32b721995f355eea411340e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a76ffd241623ec4ee9fd08876464def3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2947ca8e0cdbeb4aab80ce9e7b63ba98.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67306e4c11034d33babf27e837f9e4dc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/50e8c257f5615d30660cef4157c6b273.png)
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【推荐1】实验证明,平面镜反射光线的规律是:射到平面镜上的光线和被反射出的光线与平面镜所夹的锐角相等.如图1,一束光线m射到平面镜
上,被
反射后的光线为n,则入射光线m、反射光线n与平面镜
所夹的锐角
.
、
是平行放置的两面平面镜.已知光线沿直线m进入潜望镜,最后沿直线n射出,求证:
.
(2)显然,改变两面平面镜
、
之间的位置关系,经过两次反射后,入射光线m与反射光线n之间的位置关系会随之改变,如图3,一束光线m射到平面镜
上,被
反射到平面镜
上,又被
反射.若被
反射出的光线n和光线m平行,且
,则
______
,
_____
.
(3)请你猜想:图3中,当两平面镜
、
的夹角
_____
时,可以使任何入射光线m经过平面镜
、
的两次反射后,与反射光线n平行,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e53497af8899cb299d762f1a4f46a55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c9c8210eadb24a76eccacaaff9ef9df9.png)
(2)显然,改变两面平面镜
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.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/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6068c3902f2e4cb3d3df10e9413adbf1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/39ce3b2c88f555f559faa3ae26377959.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83873a9d782f2588c5eedbfe73f9bc2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4db07c6ce6c8b0e96a3470c6a3491334.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83873a9d782f2588c5eedbfe73f9bc2f.png)
(3)请你猜想:图3中,当两平面镜
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4db07c6ce6c8b0e96a3470c6a3491334.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83873a9d782f2588c5eedbfe73f9bc2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
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【推荐2】△ABC中,∠ACB=90°,AC=BC,延长AB到D,使得DB=AB,连接CD,以CD为直角边作等腰Rt△CDE,其中∠DCE=90°,连接BE.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/5/2577c1e9-8320-46f2-b5a1-71ac90b97445.png?resizew=159)
(1)猜想线段BE与AD的数量和位置关系,并说明理由;
(2)若AC=
cm,则BE=_______cm,DE=_______cm.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/5/2577c1e9-8320-46f2-b5a1-71ac90b97445.png?resizew=159)
(1)猜想线段BE与AD的数量和位置关系,并说明理由;
(2)若AC=
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf298f00799cbf34b4db26f5f63af92f.png)
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【推荐1】小明用四根长度相同的木条制作了能够活动的菱形学具,他先活动学具成为图1所示菱形,并测得
,对角线
,接着活动学具成为图2所示正方形.求图2中对角线
的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/32436704a722d5e568ff5c175bf3c662.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/75ec1c73794dca0a18c1ec510398ccff.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/17/84da141a-737c-4934-b37e-919342dad542.png?resizew=220)
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【推荐2】综合与实践
如图1,
是等边三角形,点D是
上一点,点F是
上一点,连接
,以
为边作等边三角形
,连接
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/6/9f223650-7947-4e81-9153-c945ebb60c22.png?resizew=429)
(1)如图2,当点F与点B重合时,求证:
.
(2)如图1,当点F与点B不重合时,试说明
.
(3)如图3,点F与点B重合,
与
交于点G,当点D是
的中点时,若
,请直接写出
的长.
如图1,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.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/00bab17635a999236e8d2e35017a208d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/00bab17635a999236e8d2e35017a208d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08052a312e4a29b6840a78850d666d92.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/6/9f223650-7947-4e81-9153-c945ebb60c22.png?resizew=429)
(1)如图2,当点F与点B重合时,求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d42218a68301d770accaaefb96b19f8a.png)
(2)如图1,当点F与点B不重合时,试说明
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e030fa6691152448bef3f5517363b331.png)
(3)如图3,点F与点B重合,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc34db5860990e51ba31edc8cdd077c2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/06e322e0c87479bba874db9ae9ba36b5.png)
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【推荐1】(感知)如图①,在四边形
中,点
在边
上(点
不与点
、
重合),
.易证:
∽
.
(探究)如图②,在四边形
中,点
在边
上(点
不与点
、
重合),
.
(1)求证:
∽
;
(2)若
,
,
,求
的长;
(应用)如图③,在
中,
,
,点
在边
上(点
不与点
、
重合),连接
,作
,
与边
交于点
,当
是等腰三角形时,求
的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.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/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8f8e63c767b1a19f79285d123c080211.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a24ccfcaf912d8812d127d1c6c99ca91.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2f8c7c8c8702adfbd6bcacc94a6bc661.png)
(探究)如图②,在四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.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/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/71e7fea3b9599d8021cc551f8d93e524.png)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a24ccfcaf912d8812d127d1c6c99ca91.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2f8c7c8c8702adfbd6bcacc94a6bc661.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/58fc6a5e71fa379d613ac1ef1cdf1048.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1033807076d59d5b26e1a07536688b13.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/07160f14b3b453bebb64cb2bf96dc85a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20a541b81584a032f571159ea152c85a.png)
(应用)如图③,在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/46de792a9388bc13e70dc28eeab60405.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/78b65065ec3a0cb4b050989165c003d1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.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/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63a253c7fdf589ee3dece13d5b5b5732.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d9f9b23edebed6f00741022b69727de3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc5adb5eb60ae4435a12d93854066298.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c1db14832ae7f18ca546fa577393646e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20a541b81584a032f571159ea152c85a.png)
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【推荐2】常用的分解因式的方法有提取公因式法、公式法及十字相乘法,但有更多的多项式只用上述方法就无法分解,如
,我们细心观察这个式子就会发现,前两项符合平方差公式,后两项可提取公因式,前后两部分分别分解因式后会产生公因式,然后提取公因式就可以完成整个式子的分解因式了。
过程为:
;
这种分解因式的方法叫做分组分解法,利用这种方法解决下列问题:
(1)分解因式:
;
(2)
三边a,b,c满足
,判断
的形状.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2fc307ac5989e51ab0ed5d4c025355ba.png)
过程为:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/41ce5b79f4d0ffe99101316ab938e844.png)
这种分解因式的方法叫做分组分解法,利用这种方法解决下列问题:
(1)分解因式:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b433a95accec7c70e99e89546526075.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5947386c57bc5feb5cb280434f6c6ff5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
您最近一年使用:0次