如图,已知∠AOB,点
是边
上一点,且∠ACD=∠AOB.
(1)尺规作图:作∠AOB的平分线OE,交CD于点E.(保留作图痕迹,不写作法)
(2)在(1)所作图形中,若∠AOB=30°,OC=4,求△OCE的面积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef4113c492885ba7c47fe42ac792578f.png)
(1)尺规作图:作∠AOB的平分线OE,交CD于点E.(保留作图痕迹,不写作法)
(2)在(1)所作图形中,若∠AOB=30°,OC=4,求△OCE的面积.
![](https://img.xkw.com/dksih/QBM/2020/1/14/2376793250816000/2377095293591552/STEM/81aa92c6145445feb9641ba19e0a92c9.png?resizew=203)
更新时间:2020-01-14 21:15:39
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【知识点】 含30度角的直角三角形解读
相似题推荐
解答题-问答题
|
适中
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【推荐1】【问题情境】在一次数学兴趣小组活动中,小昕同学将一大一小两个三角板按照如图1所示的方式摆放.其中
,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2024/4/2/2463119c-4735-431a-b07b-4d1fa2b0a2c8.png?resizew=532)
【问题探究】小昕同学将三角板
绕点B按顺时针方向旋转.
(1)如图1,
___________.
(2)如图2,当点E落在边
上时,延长
交
于点F,求
的长.
(3)若点C、E、D在同一条直线上,求点D到直线
的距离.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/74db1f028c135803c5f56852ec330d01.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56d3c9ce32b721995f355eea411340e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b851659bf075193b525317cf21659d2.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/4/2/2463119c-4735-431a-b07b-4d1fa2b0a2c8.png?resizew=532)
【问题探究】小昕同学将三角板
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ab8a10e675354fa0c6e7da3d06b999d.png)
(1)如图1,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c978d92edf0c4c1ef8620c17df75d35e.png)
(2)如图2,当点E落在边
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/274cf35acb4a1748d15c39d15a9bea7b.png)
(3)若点C、E、D在同一条直线上,求点D到直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
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解答题-证明题
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名校
【推荐2】已知
为线段
的中点,
,
为线段
上一动点(不含点
),点
在射线
上,连接
,记
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/13/295123cb-8295-461c-bab8-007f238acd39.png?resizew=290)
(1)如图①,当
,
时,求证:
.
(2)在(1)的条件下,当
时,
______.
(3)如图②,当
,且
时,
______.
![](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/6f75e73ff704363c8f1f1db787446715.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db54223bb3fc2fe2497213a4d1f94827.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/803d95b199f7e2b8d5eec8f71c5d4a31.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/75d358d093f81f03de1a9d3813d6c90a.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/13/295123cb-8295-461c-bab8-007f238acd39.png?resizew=290)
(1)如图①,当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97cf714ffb3fd5917a76b191640b55fe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5095a28bb1b91bf6bed9e2cfbd76bb18.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/834c5dd2c851131fd870d32d777c757b.png)
(2)在(1)的条件下,当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7759381a6f0539c063aa5c8f42eda10d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ec41b2572323b96d2f5faeb54582596.png)
(3)如图②,当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c69a23d106fd34aa17b22e9c9a8de36.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/834c5dd2c851131fd870d32d777c757b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd707b69a11f8de5566f23c1a2a9ff5a.png)
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