综合与实践
在综合与实践活动课上,老师让同学们以“三角形纸片的折叠、旋转”为主题开展数学活动,探究线段长度的有关问题. 动手操作:
第一步:在图1中,测得三角形纸片ABC中,∠ACB=60°,BC<AC.
第二步:将图1中的△ABC纸片折叠,使点B落在边AC上的点E处,然后展平,得到折痕CD,连结BE、DE,如图2. 解决问题,请根据图2完成下列问题.
![](https://img.xkw.com/dksih/QBM/2021/12/27/2881593795026944/2887084189540352/STEM/46e6abe7-1230-419a-a692-8020df03fcef.png?resizew=233)
(1)BD____DE(请正确选择“>”、“=”、“<”中的一个);
(2)试判断△BCE 的形状,并给予证明;
(3)若BC=6,则△BCE 的外接圆的半径为_____.
在综合与实践活动课上,老师让同学们以“三角形纸片的折叠、旋转”为主题开展数学活动,探究线段长度的有关问题. 动手操作:
第一步:在图1中,测得三角形纸片ABC中,∠ACB=60°,BC<AC.
第二步:将图1中的△ABC纸片折叠,使点B落在边AC上的点E处,然后展平,得到折痕CD,连结BE、DE,如图2. 解决问题,请根据图2完成下列问题.
![](https://img.xkw.com/dksih/QBM/2021/12/27/2881593795026944/2887084189540352/STEM/46e6abe7-1230-419a-a692-8020df03fcef.png?resizew=233)
(1)BD____DE(请正确选择“>”、“=”、“<”中的一个);
(2)试判断△BCE 的形状,并给予证明;
(3)若BC=6,则△BCE 的外接圆的半径为_____.
21-22九年级上·黑龙江齐齐哈尔·期中 查看更多[4]
黑龙江省讷河市第三中学2021-2022学年九年级上学期期中考试数学试题(已下线)专题2.47 圆中的折叠问题(基础练)-2023-2024学年九年级数学上册基础知识专项突破讲与练(苏科版)(已下线)专题2.11 确定圆的条件(分层练习)(基础练)-2023-2024学年九年级数学上册基础知识专项突破讲与练(苏科版)(已下线)专题24.53 圆中的折叠问题(基础练)-2023-2024学年九年级数学上册基础知识专项突破讲与练(人教版)
更新时间:2022-01-04 10:10:43
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【推荐1】如图,在Rt△ABC中,∠ACB=90°,∠BAC=30°,将线段CA绕点C逆时针旋转60°,得到线段CD,连接AD,BD.
(1)依题意补全图形;
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【推荐2】如图,在
和
中,
,
,垂足为
,
,点E、F分别在AB和AC上,且满足
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(1)求证:
是等边三角形.
(2)求证:
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(1)求证:
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【推荐1】如图,在△ABC中,∠A=90°,点D为AB上一点,沿CD折叠△ABC,点A恰好落在BC边上的A’处,AB=4,BC=5,求BD的长.
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【推荐2】如图,将一张长方形纸片
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(1)求证:
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(2)求线段
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解答题-作图题
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【推荐1】已知,如图,点A为⊙O上的一点
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【推荐2】如图,在
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保留作图痕迹,不写作法
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解答题-问答题
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【推荐1】折纸,常常能为证明一个命题提供思路和方法.例如,在
中,
(如图
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沿
的平分线
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上的点
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【感知】(1)如图2,在
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【探究】(2)若将图2中
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解答题-证明题
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【推荐2】[问题背景]
如图①,将
沿折痕
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如图①,将
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[变式运用]
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