如图,在平行四边形ABCD中,AB⊥AC,点O是AC的中点,过点O作EF
AB交AD于点E,交BC于点F,连接AF.
(1)求证:AE=AF;
(2)若∠ACB=30°,BC=3,求OE的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895d6f710d5f67e1d4c7408d50d77281.png)
(1)求证:AE=AF;
(2)若∠ACB=30°,BC=3,求OE的长.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/24/f3e9784c-ba1f-4fc6-953e-3836ad2aec46.png?resizew=244)
更新时间:2021-08-21 21:45:03
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解答题-作图题
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【推荐1】下面是小明设计的“三角形一边上的高”的尺规作图:
根据小明的作法解决下面问题:
(1)利用直尺和圆规补全图形(要求保留作图痕迹)
(2)小明给出作图设计的理由如下:
连接
,![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
点
在线段
的垂直平分线上(依据1)
同理可证:点
也在线段
的垂直平分线上
垂直平分
(依据2)
线段
是
的边
上的高.
上面说理过程中的“依据1”,“依据2”分别指什么?
已知:![]() 求作: ![]() ![]() ![]() 作法:(1)分别以 ![]() ![]() ![]() ![]() ![]() (2)作直线 ![]() ![]() ![]() 所以,线段 ![]() ![]() |
(1)利用直尺和圆规补全图形(要求保留作图痕迹)
(2)小明给出作图设计的理由如下:
连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/85c4bdfb0db1e31e8459df1d15f9ab55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4eedae8d316c76e3d0b451256de03fb9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/317a01ef0a5dad45b34f33e5492a0d84.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2de0d10ef8b748d4531250c37c5d3f9e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
同理可证:点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e8d4ba86966baab5a804414573ca070.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2de0d10ef8b748d4531250c37c5d3f9e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
上面说理过程中的“依据1”,“依据2”分别指什么?
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解答题-问答题
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【推荐2】已知:在
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于
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【推荐1】如图,沿
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【推荐2】如图,△ABC是⊙O的内接三角形,BD为⊙O的直径,过点C作CE⊥BD,垂足为E.
(1)求证:∠BAC=∠BCE;
(2)若∠BAC=60°,CE=3,求BD的长.
(1)求证:∠BAC=∠BCE;
(2)若∠BAC=60°,CE=3,求BD的长.
![](https://img.xkw.com/dksih/QBM/2021/5/2/2712436874182656/2715241597771776/STEM/e236b41acd514feea89e92620ebf5815.png?resizew=162)
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解答题-证明题
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【推荐1】已知:如图,在平行四边形
中,
分别是
和
的角平分线,交
于点E,F连接
.
![](https://img.xkw.com/dksih/QBM/2023/1/3/3144733744005120/3145756721045504/STEM/554037ff08da424a8eb740ecf2cef509.png?resizew=165)
(1)求证:
互相平分;
(2)若
,求四边形
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(1)求证:
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(2)若
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解答题-证明题
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【推荐2】如图,将
ABCD沿过点A的直线
折叠,使点D落到AB边上的点
处,折痕
交CD边于点E,连接BE
是平行四边形
(2)若BE平分∠ABC,求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81a5328919a7cec382c2e91c9c528fc1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49087337d49e00990f1725c3b1f3df57.png)
(2)若BE平分∠ABC,求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e4ac0d942636f956146beb37e61ecbf.png)
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