如图,在平行四边形ABCD中,过点A作
,垂是为E,连接DE,F为线段DE上一点,且∠AFE=∠B
![](https://img.xkw.com/dksih/QBM/2021/11/5/2844936624799744/2927516426403840/STEM/b909bfbb-34da-46a1-91f9-5aeeb72e7524.png?resizew=183)
(1)求证:
;
(2)若
,求∠ADE的度数.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3e3f5dc11efe60b4fd9a13b1d6b83842.png)
![](https://img.xkw.com/dksih/QBM/2021/11/5/2844936624799744/2927516426403840/STEM/b909bfbb-34da-46a1-91f9-5aeeb72e7524.png?resizew=183)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2cbbffa750cd58fa55b2ad4e4b7534e.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1c3b8c8b061e8b1f68493797cdecb70a.png)
20-21九年级上·河北石家庄·期中 查看更多[2]
更新时间:2022-03-02 13:10:19
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解答题-证明题
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【推荐1】爱好思考的小茜在探究两条直线的位置关系查阅资料时,发现了“中垂三角形”,即两条中线互相垂直的三角形称为“中垂三角形”.如图(1)、图(2)、图(3)中,AF、BE是△ABC的中线,AF⊥BE于点P,像△ABC这样的三角形均为“中垂三角形”.设BC=a,AC=b,AB=c.
![](https://img.xkw.com/dksih/QBM/2022/3/29/2946489031540736/2965653492981760/STEM/e0aaf328a7bb497ba03066f6191cdc1e.png?resizew=324)
【特例探究】
(1)如图1,当∠PBA=45°,c=4
时,a= ,b= ;
如图2,当∠PAB=30°,c=2时,a= ,b= ;
【归纳证明】
(2)请你观察(1)中的计算结果,猜想a2、b2、c2三者之间的关系,用等式表示出来,并利用图3证明你的结论.
![](https://img.xkw.com/dksih/QBM/2022/3/29/2946489031540736/2965653492981760/STEM/e0aaf328a7bb497ba03066f6191cdc1e.png?resizew=324)
【特例探究】
(1)如图1,当∠PBA=45°,c=4
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf298f00799cbf34b4db26f5f63af92f.png)
如图2,当∠PAB=30°,c=2时,a= ,b= ;
【归纳证明】
(2)请你观察(1)中的计算结果,猜想a2、b2、c2三者之间的关系,用等式表示出来,并利用图3证明你的结论.
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【推荐2】(1)【操作发现】:如图一,在矩形
中,E是
的中点,将
沿
折叠后得到
,点F在矩形
内部,延长
交
于点G.猜想线段
和
的数量关系并证明;
(2)【类比探究】:如图二:将(1)中的矩形
改为平行四边形,其它条件不变,(1)中的结论是否仍然成立?请说明理由;
(3)【拓展应用】如图三,将(1)中的矩形
改为正方形,边长
,其它条件不变,求线段
的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e742966e3711cfa53dce04022acf4bcc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca2698f08d94afa1cd5b81444791f4c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6aa2b5e09f8ec785c59900a529390a02.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0e57a13c665af88f326c9890072bf73.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f8e5f736b1195fef1d2d300168a795f1.png)
(2)【类比探究】:如图二:将(1)中的矩形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
(3)【拓展应用】如图三,将(1)中的矩形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54275b7e571660d0a9e0370fbfe5050b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f8e5f736b1195fef1d2d300168a795f1.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/8/17/11d429db-70a8-4486-8a59-4acefb0f912a.png?resizew=403)
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真题
【推荐1】现有一块等腰三角形板,量得周长为32cm,底比一腰多2cm,若把这个三角形纸板沿其对称轴剪开,拼成一个四边形,请画出你能拼成的各种四边形的示意图,并计算拼成的各个四边形的两条对角线长的和.
![](https://img.xkw.com/dksih/QBM/2012/8/4/1573477194711040/1573477235097600/STEM/3cd72624d60443058dfb08aa8fe45a15.png)
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【推荐2】在
中,
的平分线交
于点
,交
的延长线于点
,分别过点
,
作
,
.
(1)如图
,求证:四边形
是菱形;
(2)如图
,当点
是
的中点时,连接
.若
,求
的长;
(3)如图
,当
是矩形时,连接
,交
于点
,连接
.若
,
,求
的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5138a9f70d5e8b0580e30fef6eb7baef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d39b8d91afc34e4a9b0fdbb6bafb9087.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.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/1cf483fe44e313add95210780db5db27.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d004acbe0ae03123b00767ea7e38223.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/9/11619476-4711-4fde-bcad-223d90643e1a.png?resizew=467)
(1)如图
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e1c9ae241fd78126274c65e17990c88.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/25ae006f399a4b83fb384de288c860b0.png)
(2)如图
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c650fe55b7603f106c53ca2423451c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77a7e4a6765ce78b05ee97764771e01f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b25ab66d2859ddb0a19470c65b430ec3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
(3)如图
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f82e415812cca9545611c0faa0c01b1c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5138a9f70d5e8b0580e30fef6eb7baef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e72b2e1ff83e95df048745322982451.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/274cf35acb4a1748d15c39d15a9bea7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e5a122e25cf4eb9f03ffe5ec823bfc31.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcd0ced286a0fbc7e4862f8147264277.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e65a3e478bb87d094e3a0af30dd10ae8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/828628c0876b45381c9a0edeb0fec236.png)
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名校
【推荐1】如图,已知
为
直径,点
为弧
的中点,
为弦,过点
作
的垂线,垂足为
.
;
(2)如图2,连接
,
的度数;
(3)如图3,在(2)的条件下,延长
交
于
,交
于
,过
作
的垂线交
于
,交
于点
,连接
,若
,
(
),求
的度数.
![](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/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/686171942bd7698035016c732db43b63.png)
(2)如图2,连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a299d2b999568e80be8005565ba209a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bb0dbbb82da8ef16630787676f246103.png)
(3)如图3,在(2)的条件下,延长
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e69d2b798744645af88a4fa411344a83.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b68df477b3ee45ac0f725db00d465a1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/307bd991211ec79b47a4be52933bb8e7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cdc8975e673f7ac54a81f798ce3ab267.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2bea52511a5f3f478058c853e2b33908.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dc537b7eaafcc9dcf0f8dfd3d80ffcbc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3e837f243cac3b0e84fc75b1dc715673.png)
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【推荐2】如图,点I是△ABC的内心,AI的延长线交边BC于点D,交△ABC的外接圆于点E.
(1)求证:IE=BE;
(2)若IE=4,AE=8,求DE的长.
(1)求证:IE=BE;
(2)若IE=4,AE=8,求DE的长.
![](https://img.xkw.com/dksih/QBM/2019/2/23/2146747863711744/2147481582247936/STEM/29c6b87ada874415a64a8603c9d4f025.png?resizew=96)
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名校
【推荐1】我们定义:如图1,在△ABC中,把AB点绕点A顺时针旋转
得到
.把AC绕点A逆时针旋转
得到
,连接
.当
=180°时,我们称△
是△ABC的“旋补三角形”,△A
边
上的中线AD叫做△ABC的“旋补中线”,点A叫做“旋补中心”.
特例感知:
(1) 在图2,图3中,△A
是△ABC的“旋补三角形”,AD是△ABC的“旋补中线”
① 如图2,当△ABC为等边三角形时,AD与BC的数量关系为AD= BC.
②如图3.当∠BAC=90°,BC=8时,则AD长为
[猜想论证]
(2) 在图1中,当△ABC为任意三角形时,猜想AD与BC的数量关系,并给予证明.
[拓展应用]
(3) 如图4,在四边形ABCD内部恰好存在一点P,使△PDC是△PAB的“能补三角形”,自行补图形,∠C=90°,∠D=150°,BC=12,CD=
,AB=2
.直接写出△PAB的“旋补中线”长是
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e36471e4e7749cd8da4bc9b4b3dc85fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/59ac8c5700ce2de9a140c4adea742168.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b5858ee1ce52b251816757257a11c29.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ecbed9cb44cd1f0bad05d3db2ffff18.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54f3cbee923ebf5179770f7dbb53b38f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8dc4c63a548b91061528aa11058de75.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2d59152f6b55e50dffbc6e9cda21fde.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54f3cbee923ebf5179770f7dbb53b38f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54f3cbee923ebf5179770f7dbb53b38f.png)
特例感知:
(1) 在图2,图3中,△A
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54f3cbee923ebf5179770f7dbb53b38f.png)
① 如图2,当△ABC为等边三角形时,AD与BC的数量关系为AD= BC.
②如图3.当∠BAC=90°,BC=8时,则AD长为
[猜想论证]
(2) 在图1中,当△ABC为任意三角形时,猜想AD与BC的数量关系,并给予证明.
[拓展应用]
(3) 如图4,在四边形ABCD内部恰好存在一点P,使△PDC是△PAB的“能补三角形”,自行补图形,∠C=90°,∠D=150°,BC=12,CD=
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/985f75c624e091eca4809b1dd94f0530.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9766dfef2a4159f49c7bd349fb36d670.png)
![](https://img.xkw.com/dksih/QBM/2020/10/26/2579559719550976/2580738071461888/STEM/a89e26e3602241828651e14976d57b55.png?resizew=479)
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解题方法
【推荐2】在
中,
,点
与点
在
同侧,
,且
.过点
作
交
于点
,过
作
交
于点
,连接
.
![](https://img.xkw.com/dksih/QBM/2021/5/2/2712389975851008/2716883679830016/STEM/3dcb7db0-f24f-48eb-b943-64d73183ce19.png)
(1)当
时,求
的度数.
(2)当
时;
①求证:
.
②求证:
.
③当
为多少度时,
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd967903ed5a6f640a5b801ec8be0070.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ed8f7d3d7043d4b1eb98fc5c4e2fcd3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/659211b7ad55a706609696bfc9ff61e1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/236c134aad7d9a21c49c07e924b9a531.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/91d90ea3ea4cb36f07b00a556e21c4fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/673ca30365871b48e354d5d8a58780ee.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/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c6c071b5f83d9625c8de1e9dc8e4e3bc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be2e2c0d4ac2bd79f6cea7a9b1a50662.png)
![](https://img.xkw.com/dksih/QBM/2021/5/2/2712389975851008/2716883679830016/STEM/3dcb7db0-f24f-48eb-b943-64d73183ce19.png)
(1)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e76b85d73c5b8ab8c980fe93d693acde.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d29e7c4d6216690152430b09f9cf0c2.png)
(2)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3202b1d9f838c32ab5765ce647d96b6e.png)
①求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a702c324e0c76150540c3d32df802077.png)
②求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/031e4dc3f118b3c63e532e2928accdb7.png)
③当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/af352264c963f55542ede0a7cbea57c6.png)
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