如图①,已知线段AB=20cm,点C为AB上的一个动点,点D,E分别是AC和BC的中点
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/8/f39d7fa6-774a-4a6d-a9ee-7ac924fa6194.png?resizew=443)
(1)若点C恰好是AB中点,则DE的长是多少?(直接写出结果)
(2)若BC=14cm,求DE的长
(3)试说明不论BC取何值(不超过20cm),DE的长不变
(4)知识迁移:如图②,已知∠AOB=130°,过角的内部任一点C画射线OC,若OD,OE分别平分∠AOC和∠BOC,试求出∠DOE的大小,并说明∠DOE的大小与射线OC的位置是否有关?
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/8/f39d7fa6-774a-4a6d-a9ee-7ac924fa6194.png?resizew=443)
(1)若点C恰好是AB中点,则DE的长是多少?(直接写出结果)
(2)若BC=14cm,求DE的长
(3)试说明不论BC取何值(不超过20cm),DE的长不变
(4)知识迁移:如图②,已知∠AOB=130°,过角的内部任一点C画射线OC,若OD,OE分别平分∠AOC和∠BOC,试求出∠DOE的大小,并说明∠DOE的大小与射线OC的位置是否有关?
更新时间:2019-01-10 18:11:05
|
相似题推荐
解答题-作图题
|
适中
(0.65)
【推荐1】如图,点
在线段
上,点
是线段
的中点,
.
(1)尺规作图:延长线段
,并在延长线上作一点
,使得
;(不写作法,保留作图痕迹)
(2)在(1)的条件下,若
,求线段
的长度.
![](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/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/305a88d4e0249bd16d48eda01331d2d4.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/8/22/ddc34d29-34a1-488a-9724-6eba9188a7c5.png?resizew=177)
(1)尺规作图:延长线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/55d10e2f27e6eb6d3a9901e82b3b48c7.png)
(2)在(1)的条件下,若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/239398c7334f39ef772480f69198744e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
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解答题-证明题
|
适中
(0.65)
【推荐2】已知:如图,点A,B, C, D在一条直线上, AB=CD ,
, 且AE=DF.求证:∠E=∠F.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9259585a4d047e0dc597f705b4acf334.png)
![](https://img.xkw.com/dksih/QBM/2020/11/17/2594896530276352/2597848010522624/STEM/51c11a73-886d-4409-88a4-9414a89e788b.png)
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解答题-计算题
|
适中
(0.65)
【推荐1】如图,已知点C在线段AB上,线段AC=6厘米,BC=4厘米,点M,N分别是AC,BC的中点.
![](https://img.xkw.com/dksih/QBM/2017/11/18/1819670389678080/1820712267915264/STEM/d3eb81d990ef449eb84a5be7d827d514.png?resizew=188)
(1)求线段MN的长度;
(2)根据第(1)题的计算过程和结果,设AC+BC=a,其他条件不变,你能猜出MN的长度吗?请用一句话表述你发现的规律.
![](https://img.xkw.com/dksih/QBM/2017/11/18/1819670389678080/1820712267915264/STEM/d3eb81d990ef449eb84a5be7d827d514.png?resizew=188)
(1)求线段MN的长度;
(2)根据第(1)题的计算过程和结果,设AC+BC=a,其他条件不变,你能猜出MN的长度吗?请用一句话表述你发现的规律.
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解答题-问答题
|
适中
(0.65)
【推荐2】如图,已知射线
,点P是线段
上一点,点C是线段
上一点,请完成下列作图与填空:
上的B点的右边,求作线段
,使
;(只保留作图痕迹,并标上字母,不写作法,不下结论)
(2)已知
,若点P是线段
的中点,
,
,求线段
的长度.
请完成下列填空:
解:
点P是线段
的中点,
① .
,
②
.
,
③
.
④ ,
.
⑤ ![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a16b0662e433acab49e036027e336ae8.png)
⑥
.
![](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/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb6ede9761b5b90f8dc137708e1ee90f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/710406f299b163ccde4cb7aae0b976de.png)
(2)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/710406f299b163ccde4cb7aae0b976de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3433f3d99b827bb05e87d92faaf89f42.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04f70efd7e7ffab79a90aa4f3674d196.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/84d454c82d9e52747563d47b68099249.png)
请完成下列填空:
解:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/16f3d198e76391779fa3badc848c8ac8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc4b5c9c1fbb62704324dca0fd1f06fb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/57a9fa1612a604484387c1b5ef75feb0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1ea2ca93e2a7ef77bb477ad607eb549c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9efa9fbcfb9595e2f031aa691db4564b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/75262753d497fdee640aa2907e6e1971.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0704f5c2d3e232c5b1b9d976a55e4d09.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2de355fd5af5df8edcbc5e1a6a6ab90.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/093a0780c2833f42245f151afce87516.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a61fd07bf611cb9d3f4fd05933fd2c0a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/646e2fa73dea06e37f679127de565ef9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a16b0662e433acab49e036027e336ae8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6706fe00b4e231e62d9ecbec567d526b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9efa9fbcfb9595e2f031aa691db4564b.png)
您最近一年使用:0次
解答题-问答题
|
适中
(0.65)
【推荐1】如图1.直角三角板
的直角顶点
在直线
上,线段
,
是三角板的两条直角边,射线
是
的平分线.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/16/212d029d-cc74-4f9c-b37b-2392d39d3db8.png?resizew=324)
(1)当
时,则
°;
(2)
时,则
(用含
的式子表示);
(3)当三角板绕点
逆时针旋转到图2位置时,
,其它条件不变,则
(用含
的式子表示).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6bf126cfed85fa9b7720ec6f7b0008dc.png)
![](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/683c590673eece14fea3319c4fd5eb55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a299d2b999568e80be8005565ba209a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42e7b8a59f8d66176463f3d71f882a26.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/16/212d029d-cc74-4f9c-b37b-2392d39d3db8.png?resizew=324)
(1)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/299c04e41db97ebe1f9d38ae8ccc26c4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c35b6af1d4f447760a2dc8b10a9e9afd.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6ca2a90dce96b8c1dbfca17590c611a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c35b6af1d4f447760a2dc8b10a9e9afd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83873a9d782f2588c5eedbfe73f9bc2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b5858ee1ce52b251816757257a11c29.png)
(3)当三角板绕点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6ca2a90dce96b8c1dbfca17590c611a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c35b6af1d4f447760a2dc8b10a9e9afd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83873a9d782f2588c5eedbfe73f9bc2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5b5858ee1ce52b251816757257a11c29.png)
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解答题-作图题
|
适中
(0.65)
【推荐2】已知直线
与射线
相交于点
.
(1)如图,
,射线
平分
,求
的度数;
![](https://img.xkw.com/dksih/QBM/2021/1/22/2641861997797376/2646402009874432/STEM/3f856436-c43f-4c71-a7ca-112646a57510.png)
(2)如图,
,射线
在
的内部,射线
在
的内部,且
,
.若射线
使
,请在图中作出射线
,并求出
的度数.
![](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/1dde8112e8eb968fd042418dd632759e.png)
(1)如图,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4a1355d96e31c41efe988488c0a461d0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/683c590673eece14fea3319c4fd5eb55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fed1f57a835af4e9022e27603d12d31.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dc9f91270ddbe1cf3c1362e1b95aee14.png)
![](https://img.xkw.com/dksih/QBM/2021/1/22/2641861997797376/2646402009874432/STEM/3f856436-c43f-4c71-a7ca-112646a57510.png)
(2)如图,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f94438615778d57a6363a92be3679c05.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/683c590673eece14fea3319c4fd5eb55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fed1f57a835af4e9022e27603d12d31.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a299d2b999568e80be8005565ba209a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d22df2977de56cc69be0c1e847653d7a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/da92fe11e1b419a6d352158cf7990ef0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1503e8315e42b3aed6820075241a8e12.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6cad4595d5352b2884568a59d8d766a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b76f71e580e31642cddf4b5b7fe380f7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6cad4595d5352b2884568a59d8d766a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/843adec8fba1741ccb81a9017cfb815f.png)
![](https://img.xkw.com/dksih/QBM/2021/1/22/2641861997797376/2646402009874432/STEM/229396a5-4823-44ea-8462-22ccd0fac3d1.png)
您最近一年使用:0次
解答题-问答题
|
适中
(0.65)
【推荐3】如图1,
为直线
上一点,过点
在直线
上方作射线
,
.将直角三角板
的直角顶点放在点
处,一条边
在射线
上,另一边
在直线
上方,将直角三角板绕点
按每秒
的速度逆时针旋转一周,设旋转时间为
秒.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/16/4109a331-6984-426a-afd8-ca9a5334fd08.png?resizew=532)
(1)如图2,当
时,
___________,
___________,
___________;
(2)当三角板旋转至边
与射线
相交时
如图
,试猜想
与
的数量关系,并说明理由;
(3)在旋转过程中,是否存在某个时刻,使得射线
、
、
中的某一条射线是另两条射线所成夹角的角平分线?若存在,请直接写出t的取值,若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a6c6e7c025362c46a64a8956761f08e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a6c6e7c025362c46a64a8956761f08e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6967ebd791092c62b4ef97924d91883.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8d24aa2b48043dc2ec7dce441a59dd5e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/158acd5411db2a429ae6f5ae02e65e07.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ae7a3e520a16d4fdd73c4e6a4ce7be0e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6c042ff18466e8165fadf343d142a4b0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d62e8aadaadebf1454fde21a390ebdea.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a6c6e7c025362c46a64a8956761f08e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c9d6819f37b38e626e8faec7be763a9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36a1b09c653185842513e24ebba60bb3.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/16/4109a331-6984-426a-afd8-ca9a5334fd08.png?resizew=532)
(1)如图2,当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8604f98a733e417374fbda22b690ad3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9268f893516e6638e84f17dc82d53df1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/98f6d6dcde0b8bc7a262b941ac0427e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ea239e084d70b600be528204fe4774a2.png)
(2)当三角板旋转至边
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b79dd200766db27fb90d6bd1992cf658.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/598c4ff9fc8518fa4829e39254d3f6e5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11d71379442f28c038d367d49422cf90.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/72634560f134103c60b8cb3746d29c37.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0e18f2913e20c304a380f4d90e82c52a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/414830f16df6d76fb8d1395a95368f97.png)
(3)在旋转过程中,是否存在某个时刻,使得射线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ae7a3e520a16d4fdd73c4e6a4ce7be0e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f6967ebd791092c62b4ef97924d91883.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6c042ff18466e8165fadf343d142a4b0.png)
您最近一年使用:0次
解答题-问答题
|
适中
(0.65)
【推荐1】如图,直线
相交于点
,
平分
,且
.
(1)求
的度数;
(2)若
平分
,求
的度数.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e85814f051a479a1b04a46f70e96557a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a299d2b999568e80be8005565ba209a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dc9f91270ddbe1cf3c1362e1b95aee14.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/12f269ec12011d060ce72b829d9b6cb8.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/9/8/3400923c-ae16-4b86-9682-4ba5e5587e59.png?resizew=209)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cbee6d5731d6f4bb1e4f2ba3d89b7dc.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6cad4595d5352b2884568a59d8d766a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/75f55c6ac896ab4277fae2230a6e10b0.png)
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解答题-问答题
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适中
(0.65)
【推荐2】如图,∠AOC=140°,OD平分∠AOC,OB⊥OA,垂足为O.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/9/19/b9040fc6-fba3-48c4-86ce-05b8f48f21b0.png?resizew=112)
求∠DOB的度数:(按要求填空)
解:因为OD平分∠AOC(已知)
所以∠AOD=
∠AOC( )
因为∠AOC=140°(已知)
所以∠AOD=_________°(等量代换)
又因为OB⊥OA(已知)
所以∠AOB=90°( )
所以∠DOB=∠AOB-______________=_____________°
![](https://img.xkw.com/dksih/QBM/editorImg/2022/9/19/b9040fc6-fba3-48c4-86ce-05b8f48f21b0.png?resizew=112)
求∠DOB的度数:(按要求填空)
解:因为OD平分∠AOC(已知)
所以∠AOD=
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e244c12208e7c6a01e3580d1ae9d7544.png)
因为∠AOC=140°(已知)
所以∠AOD=_________°(等量代换)
又因为OB⊥OA(已知)
所以∠AOB=90°( )
所以∠DOB=∠AOB-______________=_____________°
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解答题-作图题
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适中
(0.65)
【推荐3】已知O是直线MN上一点,∠MOA=40°,∠AOB=90°,∠COD与∠AOB都在直线MN的上方,且射线OC在射线OD的左侧.
![](https://img.xkw.com/dksih/QBM/2022/1/24/2901187402006528/2901209696083968/STEM/632ce986-9a89-4290-b11c-72a112015ca7.png?resizew=550)
(1)如图1,射线OC在∠AOB的内部,如果∠COD=90°,那么图中与∠AOC相等的角是 ,其依据是: .
(2)如图2,用直尺和圆规作∠AOB的平分线OP,如果∠COD=60°,且OC平分∠AOP,那么∠DON= °;(保留作图痕迹,不要求写出作法和结论)
(3)如果∠COD=60°,设∠AOC=m°(0<m<80,且m≠30),用含m的式子表示∠BOD的度数.(直接写出结论)
![](https://img.xkw.com/dksih/QBM/2022/1/24/2901187402006528/2901209696083968/STEM/632ce986-9a89-4290-b11c-72a112015ca7.png?resizew=550)
(1)如图1,射线OC在∠AOB的内部,如果∠COD=90°,那么图中与∠AOC相等的角是 ,其依据是: .
(2)如图2,用直尺和圆规作∠AOB的平分线OP,如果∠COD=60°,且OC平分∠AOP,那么∠DON= °;(保留作图痕迹,不要求写出作法和结论)
(3)如果∠COD=60°,设∠AOC=m°(0<m<80,且m≠30),用含m的式子表示∠BOD的度数.(直接写出结论)
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