1 . 我们已学习平行线的判定与性质,涉及概念同位角、内错角、同旁内角,学习该部分内容按“定义﹣判定﹣性质”三步进行.如图①,在“三线八角”中,类比内错角,具有
与
这样位置关系的角称为“外错角”,你可类比有关知识,完成涉及“外错角”的探究.
(2)探究判定:请你用已学过的平行线的判定,证明命题:外错角相等,两直线平行.
请完善证明过程.
已知:如图②,
与
是直线a、b被直线c截出的外错角,且
.
求证:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2bc8444d63d1ca92651c62fe9b220859.png)
证明:
(3)探究性质:请你用已学过的平行线的判定,证明命题:两直线平行,外错角相等.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5b69d40b75d582c4b8ffa2369af1d41.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/da2ec6f2e57f71267eda3e9f71f82f41.png)
(2)探究判定:请你用已学过的平行线的判定,证明命题:外错角相等,两直线平行.
请完善证明过程.
已知:如图②,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d5b69d40b75d582c4b8ffa2369af1d41.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d57899ad4774aed9ccc7bd23db72153.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e53497af8899cb299d762f1a4f46a55.png)
求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2bc8444d63d1ca92651c62fe9b220859.png)
证明:
(3)探究性质:请你用已学过的平行线的判定,证明命题:两直线平行,外错角相等.
您最近一年使用:0次
2 . 填空:(将下面的推理过程及依据补充完整)如图,已知:
平分
,
,
,求证:
平分
.
证明:∵______ (已知),
∴
(角平分线的定义),
∵
(已知),
∴
______,
∴______
(等量代换),
∵
(已知),
∴______
(_______),
(_______),
∴______
______(等量代换),
∴
平分
(角平分线的定义).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8fabb884dc5f9609de491245463bbe9a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43defd54316aac92a3d18d4d400033c2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9390a8688fd466fb6b883b0d60dcd872.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6beda2518cf76da94d7ec9a813dcfa82.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/10/14/fe2f265b-17ae-4a61-9000-2bf7ca4d2a39.png?resizew=135)
证明:∵______ (已知),
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f20f3632fcc7ff1804dab3f746936019.png)
∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43defd54316aac92a3d18d4d400033c2.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ccd25acdc39bf65eaf198f2b10753719.png)
∴______
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ba2383316308ad0e41faab681929f41f.png)
∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9390a8688fd466fb6b883b0d60dcd872.png)
∴______
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ba2383316308ad0e41faab681929f41f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/191496af8433cf76fc6fc93ecfc98479.png)
∴______
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6706fe00b4e231e62d9ecbec567d526b.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6beda2518cf76da94d7ec9a813dcfa82.png)
您最近一年使用:0次
3 . 填空:(将下面的推理过程补充完整)
已知:
的高AD与高BE相交于点F,过点F作
,交直线AB于点G.如图,若∠ABC=45°.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/27/6659302b-13be-47c6-a2d5-33f98782879e.png?resizew=206)
求证:(1)
;(2)
.
证明:(1)∵AD,BE为△ABC的高,
∴ ① ⊥BC,BE⊥AC,
∴
② °,
∴
,
,
③
,
∴
,
∵∠ABC=45°,
∴
④ ,
∴
,
∵在△FDB和△CDA中
,
∴
;
(2)∵
⑥ ,
∴
⑦ ,
∴
,
∴
⑧
,
∴FA=FG,
∴
⑨ + ⑩
.
已知:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a32ff42fed45ae870a688fb7103fa72.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/27/6659302b-13be-47c6-a2d5-33f98782879e.png?resizew=206)
求证:(1)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e24c6746c0b1822442b23cafe261d34.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7fc09cd4c6fa268a8daf7a693362c5e3.png)
证明:(1)∵AD,BE为△ABC的高,
∴ ① ⊥BC,BE⊥AC,
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/74d8a6a9897be4c79615e2de9bf85eed.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/53fc4a4403dea73e16bc4f211957d4c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d337410cd9456b76bbf022dcae6147d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/00348f2467cb81025a3b6f02b899dedb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b0c06422e1d55db3077257af113df4bb.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf42e334e75105daba4930d11e2b3c55.png)
∵∠ABC=45°,
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96fca16b4ce5f9ecace320187205716f.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63a1d4c140243ba9a9bd7256ec2bbce6.png)
∵在△FDB和△CDA中
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/643f0f7998fe2153ad57b26905b9f577.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4326d82b052e8aa579066bbdcbfc5417.png)
(2)∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5fb468668438ff900c2fe58ff3ff8bf6.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3e80bb0f244f283cd4c3faf809ba488d.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a95a2a2d3ead86a287255a428997c399.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2ebc3ceb9506738bfc13f0f88c3b498f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54ba82386f02b1d18b794771aa5a5edf.png)
∴FA=FG,
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e9dbe135f96bea68997799c0c559d823.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/542c8be33859cf9957aaa447f896b212.png)
您最近一年使用:0次
2022-08-27更新
|
164次组卷
|
2卷引用:辽宁省沈阳市和平区2021-2022学年七年级下学期期末数学试题
4 . 如图,
,
,求证:
.完成下面的推理过程.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/30/39b87481-5569-4bae-b6a4-d34406b436b7.png?resizew=159)
证明:∵
( ),
∴( )
(___________),
∵
(已知),
∴
(_______)(________________),
∴
(______)(______________),
∴
(______________).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd81adb13f5a7550b0f94f770900a613.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e53497af8899cb299d762f1a4f46a55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c46ce34fdc50dbd94ca84c366d6f6a47.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/30/39b87481-5569-4bae-b6a4-d34406b436b7.png?resizew=159)
证明:∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd81adb13f5a7550b0f94f770900a613.png)
∴( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0357ae3869c5f152994d6bb5d2cd7284.png)
∵
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e53497af8899cb299d762f1a4f46a55.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3cc310194575262fb45352c2fbc19868.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc521258fcaeaf7acffc5ae98c3af6d9.png)
∴
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c46ce34fdc50dbd94ca84c366d6f6a47.png)
您最近一年使用:0次
5 . 请将下列证明过程补充完整.
已知:如图,已知∠1+∠2=180°,∠3=∠B.求证:∠AED=∠ACB.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/31/a523cf4a-204d-4026-97e6-5fc142c81ad3.png?resizew=192)
证明:∵∠1+∠4=180°(平角定义),
∠1+∠2=180°(已知),
∴∠2=∠4(同角的补角相等).
∴DB∥EF(______).
∴∠3+______=∠180°(______).
又∵∠3=∠B(已知),
∴∠B+______=180°(等量代换).
∴______∥______(同旁内角互补,两直线平行).
∴∠AED=∠ACB(______).
已知:如图,已知∠1+∠2=180°,∠3=∠B.求证:∠AED=∠ACB.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/31/a523cf4a-204d-4026-97e6-5fc142c81ad3.png?resizew=192)
证明:∵∠1+∠4=180°(平角定义),
∠1+∠2=180°(已知),
∴∠2=∠4(同角的补角相等).
∴DB∥EF(______).
∴∠3+______=∠180°(______).
又∵∠3=∠B(已知),
∴∠B+______=180°(等量代换).
∴______∥______(同旁内角互补,两直线平行).
∴∠AED=∠ACB(______).
您最近一年使用:0次
2022-07-30更新
|
181次组卷
|
2卷引用:辽宁省朝阳市建平县2021-2022学年七年级下学期期末数学试题
6 . 完成下面的说理过程:(不用抄题,直接将所填内容写到答题卡上即可)
已知:如图,点
在线段
的延长线上,点
在线段
的延长线上,连接
,
,
,
.
求证:
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/9/21/b176a431-d3d9-4b02-b697-7007aed83387.png?resizew=166)
证明:因为
(______),
又因为
(已知),
所以
(等量代换),
所以
(同旁内角互补,两直线平行),
所以
(______),
因为
(已知),
所以
(等量代换),
所以
(______),
所以
(______).
已知:如图,点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7dea2ae9d515f9ab351ad72306b776ee.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e52a8f07834cbbbe4224962672fbbb2.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/0f85b53a74e2a952b581700c83bbcd25.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c4fd85cff10e8f192cfe0b0a8b2f4996.png)
求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60b333110550208ffce4ec642f78075f.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/9/21/b176a431-d3d9-4b02-b697-7007aed83387.png?resizew=166)
证明:因为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e53497af8899cb299d762f1a4f46a55.png)
又因为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85b53a74e2a952b581700c83bbcd25.png)
所以
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df4d67aa2a39c15abaa0cbc09432f1fb.png)
所以
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4adf90a8c2b29334cdc5aa5b554991f9.png)
所以
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff49350fbecbc2162b70c9f5f7e56e0c.png)
因为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c4fd85cff10e8f192cfe0b0a8b2f4996.png)
所以
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/953d6c4c714549dcc26dcf6227660a0f.png)
所以
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ada55c12a53a4c469e052445547bed96.png)
所以
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60b333110550208ffce4ec642f78075f.png)
您最近一年使用:0次
7 . 请将下列证明过程补充完整.
已知:如图,已知∠1+∠2=180°,∠3=∠B.求证:∠AED=∠ACB.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/31/a523cf4a-204d-4026-97e6-5fc142c81ad3.png?resizew=192)
证明:∵∠1+∠4=180°(平角定义),
∠1+∠2=180°(已知),
∴∠2=∠4(同角的补角相等).
∴DB∥EF(______).
∴∠3+______=∠180°(______).
又∵∠3=∠B(已知),
∴∠B+______=180°(等量代换).
∴______∥______(同旁内角互补,两直线平行).
∴∠AED=∠ACB(______).
已知:如图,已知∠1+∠2=180°,∠3=∠B.求证:∠AED=∠ACB.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/31/a523cf4a-204d-4026-97e6-5fc142c81ad3.png?resizew=192)
证明:∵∠1+∠4=180°(平角定义),
∠1+∠2=180°(已知),
∴∠2=∠4(同角的补角相等).
∴DB∥EF(______).
∴∠3+______=∠180°(______).
又∵∠3=∠B(已知),
∴∠B+______=180°(等量代换).
∴______∥______(同旁内角互补,两直线平行).
∴∠AED=∠ACB(______).
您最近一年使用:0次
8 . 完成下列证明
如图,点D,E,F分别在AB,BC,AC上,且DE//AC,EF//AB
![](https://img.xkw.com/dksih/QBM/2020/5/24/2469672456101888/2470507479719936/STEM/d11a5c35-b261-485f-afe5-75195ad3e22d.png)
求证:∠A+∠B+∠C=180°
证明:∵DE//AC,
∴∠1=________,∠4=________( )
又∵EF//AB,
∴∠3=________( )
∠2=________( )
∴∠2=∠A( )
又∵∠1+∠2+∠3=180°(平角定义)
∴∠A+∠B+∠C=180°
如图,点D,E,F分别在AB,BC,AC上,且DE//AC,EF//AB
![](https://img.xkw.com/dksih/QBM/2020/5/24/2469672456101888/2470507479719936/STEM/d11a5c35-b261-485f-afe5-75195ad3e22d.png)
求证:∠A+∠B+∠C=180°
证明:∵DE//AC,
∴∠1=________,∠4=________( )
又∵EF//AB,
∴∠3=________( )
∠2=________( )
∴∠2=∠A( )
又∵∠1+∠2+∠3=180°(平角定义)
∴∠A+∠B+∠C=180°
您最近一年使用:0次
2020-05-25更新
|
431次组卷
|
2卷引用:辽宁省抚顺市新抚区2019-2020学年七年级下学期期末数学试题
9 . 已知:如图,DE⊥AC,垂足为点E,∠AGF=∠ABC,∠BFG+∠BDE=180°,
求证:BF⊥AC.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/5/1b9adb4c-646a-4beb-8285-7db12392aecd.png?resizew=160)
请完成下面的证明的过程,并在括号内注明理由.
证明:∵∠AGF=∠ABC(已知)
∴FG∥ ( )
∴∠BFG=∠FBC( )
∵∠BFG+∠BDE=180°(已知)
∴∠FBC+∠BDE=180°( )
∴BF∥DE( )
∴∠BFA= (两直线平行,同位角相等)
∵DE⊥AC(已知)
∴∠DEA=90°( )
∴∠BFA=90°(等量代换)
∴BF⊥AC(垂直的定义)
求证:BF⊥AC.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/5/1b9adb4c-646a-4beb-8285-7db12392aecd.png?resizew=160)
请完成下面的证明的过程,并在括号内注明理由.
证明:∵∠AGF=∠ABC(已知)
∴FG∥ ( )
∴∠BFG=∠FBC( )
∵∠BFG+∠BDE=180°(已知)
∴∠FBC+∠BDE=180°( )
∴BF∥DE( )
∴∠BFA= (两直线平行,同位角相等)
∵DE⊥AC(已知)
∴∠DEA=90°( )
∴∠BFA=90°(等量代换)
∴BF⊥AC(垂直的定义)
您最近一年使用:0次
2020-03-17更新
|
263次组卷
|
2卷引用:辽宁省鞍山市台安县2018-2019学年七年级下学期期中数学试题
10 . P是∠BAC内一点,射线PD//AB,射线PE//AC,连接BC,当点D在线段BC上,点E在射线AB上时,
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/25/7b78eea4-a28f-45fe-a23e-93cbcaff2b89.png?resizew=197)
(1)补全图形;
(2)猜想∠DPE与∠A的数量关系,并证明.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/25/7b78eea4-a28f-45fe-a23e-93cbcaff2b89.png?resizew=197)
(1)补全图形;
(2)猜想∠DPE与∠A的数量关系,并证明.
您最近一年使用:0次
2022-07-18更新
|
295次组卷
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7卷引用:辽宁省大连市金普新区2021-2022学年七年级下学期期末数学试题
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