1 . 【规律探索】探索三角形的内(外)角平分线形成的角的规律:
在三角形中,由三角形的内角平分线、外角平分线所形成的角存在一定的规律.
规律1:三角形的两个内角的平分线形成的钝角等于90°加上第三个内角度数的一半;
规律2:三角形的两个外角的平分线形成的锐角等于90°减去与这两个外角不相邻的内角度数的一半
![](https://img.xkw.com/dksih/QBM/editorImg/2022/9/3/2fbfdc9f-95bd-40de-bf94-09ee81a0b491.png?resizew=385)
【问题呈现】如图1,点P是△ABC的内角平分线BP与CP的交点,点M是△ABC的外角平分线BM与CM的交点,∠P=90°+
∠A,∠M=90°-
∠A.
说明∠P=90°+
∠A如下:
∵BP ,CP分别平分∠ABC, ∠ACB,
∴∠ ABC=2∠1 , ∠ACB=2∠2.
∴∠A+2(∠1+∠2)=180°①
∴∠1+∠2=90-
∠A.
∴∠P=180—(∠1+∠2)=90°+
∠A.
请仔细阅读理解上面的说理过程,完成下列问题:
(1)上述说理过程中步骤①的依据是 .
(2)结合图1,试说明∠M=90°-
∠A.
(3)【拓展延伸】如图2,点Q是△ABC的内角平分线BQ与△ABC的外角(∠ACD)平分线CQ的交点.若∠A=50°,则∠Q的大小为___________.
在三角形中,由三角形的内角平分线、外角平分线所形成的角存在一定的规律.
规律1:三角形的两个内角的平分线形成的钝角等于90°加上第三个内角度数的一半;
规律2:三角形的两个外角的平分线形成的锐角等于90°减去与这两个外角不相邻的内角度数的一半
![](https://img.xkw.com/dksih/QBM/editorImg/2022/9/3/2fbfdc9f-95bd-40de-bf94-09ee81a0b491.png?resizew=385)
【问题呈现】如图1,点P是△ABC的内角平分线BP与CP的交点,点M是△ABC的外角平分线BM与CM的交点,∠P=90°+
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
说明∠P=90°+
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
∵BP ,CP分别平分∠ABC, ∠ACB,
∴∠ ABC=2∠1 , ∠ACB=2∠2.
∴∠A+2(∠1+∠2)=180°①
∴∠1+∠2=90-
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
∴∠P=180—(∠1+∠2)=90°+
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
请仔细阅读理解上面的说理过程,完成下列问题:
(1)上述说理过程中步骤①的依据是 .
(2)结合图1,试说明∠M=90°-
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
(3)【拓展延伸】如图2,点Q是△ABC的内角平分线BQ与△ABC的外角(∠ACD)平分线CQ的交点.若∠A=50°,则∠Q的大小为___________.
您最近一年使用:0次
2022-09-01更新
|
155次组卷
|
2卷引用:河南省南阳市淅川县2021-2022学年七年级下学期期末数学试题
2 . 如图,点O在直线
上,
是任一射线,
、
分别是
和
的平分线.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/5/406af635-48ec-4bf7-9241-77e9f7e66733.png?resizew=154)
(1)求
的度数;
(2)请用一句简洁的文字语言写出你发现的规律.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/828628c0876b45381c9a0edeb0fec236.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/683c590673eece14fea3319c4fd5eb55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a299d2b999568e80be8005565ba209a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fed1f57a835af4e9022e27603d12d31.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d22df2977de56cc69be0c1e847653d7a.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/3/5/406af635-48ec-4bf7-9241-77e9f7e66733.png?resizew=154)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cbee6d5731d6f4bb1e4f2ba3d89b7dc.png)
(2)请用一句简洁的文字语言写出你发现的规律.
您最近一年使用:0次
3 . 如图,线段
与射线
垂直,点
是射线
上一动点(与
点不重合),
的平分线与
的平分线交于点
,与
的外角
的平分线交于点
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/8/6908897b-7b27-45be-b75e-7a4b6878c000.png?resizew=200)
(1)求
的大小;
(2)当点
在射线
上运动时,
的形状是否变化?若变化,请写出它的变化规律;若不变,请写出它的形状,并说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef4113c492885ba7c47fe42ac792578f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b90e0f35eda1a729fed485f83da5ea9d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b90e0f35eda1a729fed485f83da5ea9d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/27eac848aa379fb7453ccd63f95760d5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7081dada4c2d7e8b7372637a900dbe21.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a1715eb5bb98c2f856c8979b04e1125c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df80c045c9b1d80187763406fa9deafc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/8/6908897b-7b27-45be-b75e-7a4b6878c000.png?resizew=200)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a9b4a78c3b85dafdaec2e4e6dc87bd7.png)
(2)当点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b90e0f35eda1a729fed485f83da5ea9d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6c8a8f63088245653535d5d23d6f26a8.png)
您最近一年使用:0次
2022-07-11更新
|
156次组卷
|
2卷引用:江苏省宿迁市沭阳县2021-2022学年七年级下学期期末数学试题
2022七年级上·全国·专题练习
4 . 如图,已知
,以
为顶点,
为一边画
,若
,
与
的平分线分别为
,
.
![](https://img.xkw.com/dksih/QBM/2022/12/4/3123503972540416/3136342141829120/STEM/62b17efb6cfc42d5b00ec6fbc0c58eb9.png?resizew=235)
(1)如图1,若射线
在
的内部,求
的度数.
(2)如图2,若射线
在
的外部,求
的度数.
(3)由(1)、(2)题结果中的规律,若把“
改为
为锐角)”,其余条件不变,
的度数会发生变化吗?若变化,请求
的度数;若不变,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20ccc37b189fa2cbc269ca0b233dac37.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b90e0f35eda1a729fed485f83da5ea9d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d22df2977de56cc69be0c1e847653d7a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db91877e869a8d58b2bab2c39756d7fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fed1f57a835af4e9022e27603d12d31.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d22df2977de56cc69be0c1e847653d7a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aaf3369e0ea90e8d5cf4b6b3c45c0fd8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/88e9f7d1272b7344346b58b660aa260a.png)
![](https://img.xkw.com/dksih/QBM/2022/12/4/3123503972540416/3136342141829120/STEM/62b17efb6cfc42d5b00ec6fbc0c58eb9.png?resizew=235)
(1)如图1,若射线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/828628c0876b45381c9a0edeb0fec236.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d7b2fe01a33c4825f9974ed9663a99c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/27935c1ef4df2d52ac697678a3c8f39d.png)
(2)如图2,若射线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/828628c0876b45381c9a0edeb0fec236.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d7b2fe01a33c4825f9974ed9663a99c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/27935c1ef4df2d52ac697678a3c8f39d.png)
(3)由(1)、(2)题结果中的规律,若把“
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db91877e869a8d58b2bab2c39756d7fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7b9245f2f587381f6e80fcc060eb1608.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/27935c1ef4df2d52ac697678a3c8f39d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/27935c1ef4df2d52ac697678a3c8f39d.png)
您最近一年使用:0次
22-23七年级下·全国·假期作业
5 . 如图,点
为直线
上一点,
为一射线,
平分
,
平分
.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/26/c91205e7-d71a-4ca2-adbb-0efb66faab5d.png?resizew=125)
(1)若
,试探究
,
的位置关系,并说明理由.
(2)若
为任意角
,(
)中
,
的位置关系是否仍成立?请说明理由,由此你发现了什么规律?(数学思想链接:从特殊到一般)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/828628c0876b45381c9a0edeb0fec236.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a299d2b999568e80be8005565ba209a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fed1f57a835af4e9022e27603d12d31.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6cad4595d5352b2884568a59d8d766a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d22df2977de56cc69be0c1e847653d7a.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/26/c91205e7-d71a-4ca2-adbb-0efb66faab5d.png?resizew=125)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9a71bb53109aab57cf279b83839386d2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a299d2b999568e80be8005565ba209a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6cad4595d5352b2884568a59d8d766a4.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d22df2977de56cc69be0c1e847653d7a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bb0c6b3ac303e83e204a619ac3d5e1bf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdaa19de263700a15fcf213d64a8cd57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a299d2b999568e80be8005565ba209a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6cad4595d5352b2884568a59d8d766a4.png)
您最近一年使用:0次
6 . 如图,在
中,
,
与
的平分线交于点
,
与
的平分线相交于点
,...;依此规律得
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c918a22549848476f8e45c56b2314443.png)
_____ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7661d8b8cc71e4261a3c32504377ac76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d39b8d91afc34e4a9b0fdbb6bafb9087.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdb8eca20ce2c918ea4034ea15210c7f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f9721059d158853671eaf19e39769b13.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/74036e4adc6507fe736dced0ea653576.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1189af2f5f84a64ba3836f1df1e9080d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd8db4b168ddbcba90ac9b31d36a0432.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48de3dfc7698b38fd942feab4016783f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c918a22549848476f8e45c56b2314443.png)
您最近一年使用:0次
7 . 将一副直角三角板(分别含45°,45°,90°和30°,60°,90°的角)叠放在量角器上,OE、OF分别平分∠AOB和∠COD.
![](https://img.xkw.com/dksih/QBM/2022/2/25/2923884098617344/2938045818396672/STEM/02af3332-9eff-411e-8584-0c25076a5d7c.png?resizew=689)
特例感知:
(1)如图I,若点A、O、D在同一直线上,边AO与量角器0°刻度线重合,边OD与量角器180°刻度线重合,则
;
规律探究:
(2)如图II,若两直角三角板有重叠时,
①当
时,则∠EOF=___,
②当
,则∠EOF=___(含
的式子表示);
解决问题:
(3)图I的条件下,保持三角板AOB固定不动,将三角板COD绕着点O逆时针旋转,平均每秒旋转5°,直至边OD第一次重合在边OA上,设旋转时间为t秒,在旋转过程中,是否存在某一时刻三角板COD两直角边是∠AOB的角平分线,若存在,请求出t的值;若不存在,请说明理由.
![](https://img.xkw.com/dksih/QBM/2022/2/25/2923884098617344/2938045818396672/STEM/02af3332-9eff-411e-8584-0c25076a5d7c.png?resizew=689)
特例感知:
(1)如图I,若点A、O、D在同一直线上,边AO与量角器0°刻度线重合,边OD与量角器180°刻度线重合,则
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08991e33572d0a7a830db8de33b88fe9.png)
规律探究:
(2)如图II,若两直角三角板有重叠时,
①当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1aecaf096c1a651c323965357f9c3c4.png)
②当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcbec8352ce3dbfbf3b173045d0ba8f2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
解决问题:
(3)图I的条件下,保持三角板AOB固定不动,将三角板COD绕着点O逆时针旋转,平均每秒旋转5°,直至边OD第一次重合在边OA上,设旋转时间为t秒,在旋转过程中,是否存在某一时刻三角板COD两直角边是∠AOB的角平分线,若存在,请求出t的值;若不存在,请说明理由.
您最近一年使用:0次
2022-03-17更新
|
249次组卷
|
4卷引用:河南省开封市2021-2022学年七年级上学期期末数学试题
名校
8 . 如图甲,已知线段
,
,线段CD在线段AB上运动,E,F分别是AC,BD的中点.
![](https://img.xkw.com/dksih/QBM/2022/1/21/2899406780071936/2900692594319360/STEM/84daf9c9-5937-4ccb-8894-9e519f1ccda4.png?resizew=286)
(1)若
,则
______
;
(2)当线段CD在线段AB上运动时,试判断EF的长度是否发生变化?如果不变,请求出EF的长度,如果变化,请说明理由;
(3)①对于角,也有和线段类似的规律.如图乙,已知
在
内部转动,OE,OF分别平分
和
,若
,
,求
;
②请你猜想
,
和
会有怎样的数量关系,直接写出你的结论.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9040c9795e7132ebf65ede1f98c4d72b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c52b5f8acda412ddceb94c4e4e6b7f0.png)
![](https://img.xkw.com/dksih/QBM/2022/1/21/2899406780071936/2900692594319360/STEM/84daf9c9-5937-4ccb-8894-9e519f1ccda4.png?resizew=286)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dafddfd80f69337909f6eac0f0dbfd59.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a71a9d21f77e9535de152bb33f802bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9efa9fbcfb9595e2f031aa691db4564b.png)
(2)当线段CD在线段AB上运动时,试判断EF的长度是否发生变化?如果不变,请求出EF的长度,如果变化,请说明理由;
(3)①对于角,也有和线段类似的规律.如图乙,已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed66570f697459aba9daa2eaf9460bcb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d7b2fe01a33c4825f9974ed9663a99c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fed1f57a835af4e9022e27603d12d31.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dc9f91270ddbe1cf3c1362e1b95aee14.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/86e847513a54d0e5a8433f583767ccaf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/06a327b3c7ec05a5da39530fd3b34379.png)
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2022-01-23更新
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326次组卷
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6卷引用:广西壮族自治区来宾市2021-2022学年七年级上学期期末数学试题
广西壮族自治区来宾市2021-2022学年七年级上学期期末数学试题(已下线)专题4.25 类比思想探究线段和角的大小(分层练习)(培优练)-2023-2024学年七年级数学上册基础知识专项突破讲与练(北师大版)广东省东莞市五校联考2023-2024学年七年级上学期期末数学试题广东省东莞市厚街海月学校2023-2024学年七年级上学期期末数学试题(已下线)专题4.26 类比思想探究线段和角的大小(分层练习)(培优练)-2023-2024学年七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6.29 类比思想探究线段和角的大小(分层练习)(培优练)-2023-2024学年七年级数学上册基础知识专项突破讲与练(苏科版)
9 . 如图,在
中,
,延长
到点
,
与
的平分线交于点
,得到
;
与
的平分线相交
于点
,得到
,则
=________ °;依此规律得到
,则
=________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b3c65edad25ddd666cdce0d7e5afefc9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fa6c925010aba96bf60262f27c5073ff.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d39b8d91afc34e4a9b0fdbb6bafb9087.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdb8eca20ce2c918ea4034ea15210c7f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a18722354086c42e62334983fc50eb6a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0cd3ad5297dc83de7f5591b31c5f5e59.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/74036e4adc6507fe736dced0ea653576.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1189af2f5f84a64ba3836f1df1e9080d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a18722354086c42e62334983fc50eb6a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a18722354086c42e62334983fc50eb6a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/29c79a50a42b539b28eaf9a47094398f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/29c79a50a42b539b28eaf9a47094398f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9da1ee0fb6feae43be0d715cf6059f43.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9da1ee0fb6feae43be0d715cf6059f43.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/23/d20ede0e-bb6c-48a1-be94-b971cd62d8e0.png?resizew=288)
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10 . 【原题重现】
课本第154页例2:如图1,AC、BD相交于点O,求证:
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/18/97aaa67e-9e1c-48de-98e4-f1f79fa4270b.png?resizew=154)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/18/b2d4f180-da27-4388-9893-6eca4003e827.png?resizew=161)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/18/388d3226-537d-4c42-88b8-905ee9791cfd.png?resizew=164)
某数学兴趣小组同学对此题展开了探究讨论.
(1)【解法再探】
课本利用“三角形内角和是180°”和“对顶角相等”对此题进行了证明,小明同学提出了另外一种证明方法,如下思路框图:
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/18/3a458f56-ad96-4f41-9f22-ab7253b4dc25.png?resizew=479)
完成框图填空:①______,②______,③______;
(2)【变式拓展】
小慧同学把图1中线段AC与BD相交所组成的结构称为“8字形”,她对原题进行了改编:如图2,AC、BD相交于点O,∠BAC、∠BDC的角平分线交于点P,
,
,求∠P的度数(用含
,
的式子表示).请你帮助小明完成以下问题:
小明看到图2中有两个与∠P相关的“8字形”,请你根据(1)的结论写出关于∠P的两个关系式为:①
______;②
______;
小明进一步思考:设
,
,由
,得
,③
,由①、③(或②、③)联立、转化、整理可得结论:
______;
(3)【发现生成】
小慧同学为了寻找规律,再次改变条件:如图3,AC、BD相交于点O,
,
,
,
,求
的度数(用含
,
的式子表示).请你写出解答:
(4)若把(3)中的“
”都改为“
”,则
______.(用含
,
的式子表示)
课本第154页例2:如图1,AC、BD相交于点O,求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dc6436b9c2493203d008064460c3c487.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/18/97aaa67e-9e1c-48de-98e4-f1f79fa4270b.png?resizew=154)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/18/b2d4f180-da27-4388-9893-6eca4003e827.png?resizew=161)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/18/388d3226-537d-4c42-88b8-905ee9791cfd.png?resizew=164)
某数学兴趣小组同学对此题展开了探究讨论.
(1)【解法再探】
课本利用“三角形内角和是180°”和“对顶角相等”对此题进行了证明,小明同学提出了另外一种证明方法,如下思路框图:
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/18/3a458f56-ad96-4f41-9f22-ab7253b4dc25.png?resizew=479)
完成框图填空:①______,②______,③______;
(2)【变式拓展】
小慧同学把图1中线段AC与BD相交所组成的结构称为“8字形”,她对原题进行了改编:如图2,AC、BD相交于点O,∠BAC、∠BDC的角平分线交于点P,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6988b81937a2b98659c359d9ed686146.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96128255fefba0cd356cf9562588f148.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b5858ee1ce52b251816757257a11c29.png)
小明看到图2中有两个与∠P相关的“8字形”,请你根据(1)的结论写出关于∠P的两个关系式为:①
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f90ac53c0edf181ada3b06c78cf27c1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/457310489ab177e7551b89fd37b665af.png)
小明进一步思考:设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f597657b1072e1d8aa1c754975c2c4c3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3364d86751a28bae99355744868c9b1c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dc6436b9c2493203d008064460c3c487.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f39ee2ab5002c650ea9e850784c5bfd4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8f97c571528489a639ca91b59628aa71.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b6fede7d2da3ccecf3f9d32a10346c3.png)
(3)【发现生成】
小慧同学为了寻找规律,再次改变条件:如图3,AC、BD相交于点O,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d075adb96cd79d289f8d3db15296664.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ba7680ea1f9c5dcfe097a3a2456381ec.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6988b81937a2b98659c359d9ed686146.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96128255fefba0cd356cf9562588f148.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19768d8c55deb4973820aeab7a224e6a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b5858ee1ce52b251816757257a11c29.png)
(4)若把(3)中的“
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4dac452fbb5ef6dd653e7fbbef639484.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ee6a2eba56d4f2d1670b0256b8d86b92.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b6fede7d2da3ccecf3f9d32a10346c3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b5858ee1ce52b251816757257a11c29.png)
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