已知:如图,△ABC是等边三角形,BD⊥AC,E是BC延长线上的一点,且∠CED=30°.
求证:BD=DE.
求证:BD=DE.
![](https://img.xkw.com/dksih/QBM/2019/10/17/2313750559326208/2314136904368128/STEM/773d16cbd64940678c1907c408795982.png?resizew=172)
2017·北京房山·一模 查看更多[1]
更新时间:2019-10-17 22:26:29
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【推荐1】已知:如图,D是
的BC边上的一点,
于点E,且
,
,
.
(1)求
的度数.填写下面求解过程及部分理由;
解:设
.
是
的外角,
________(________)
________
.
,
(________).
,解得
.
.
________.
![](https://img.xkw.com/dksih/QBM/2020/12/28/2623973571018752/2624786330148864/STEM/5ed8ec2c-6888-471f-91eb-482652c86aba.png)
(2)求
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
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(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/721c75fcd58d3d54260aad0f82e09e37.png)
解:设
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(2)求
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【推荐2】如图,在△ABC中,AB=AC,∠A=40°,请利用尺规作图法在边AC上求作一点D,使∠DBC=35°(保留作图痕迹,不写作法).
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解答题-证明题
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【推荐1】如图,已知
,作
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(1)猜想
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【推荐2】如图,在△ABC中,∠ABC和∠ACB的角平分线交于点F,DE过点F且平行于BC.
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(1)判断三角形BDF的形状,并证明.
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【推荐1】如图,△ABC≌△ADE中,BA⊥AE,∠BAC=30°,AD=5,求BD的长.
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【推荐2】如图,已知圆O的直径
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