一、选择题:本大题共10小题,每小题3分,共30分.在每小题给出的四个选项中,只有一项是符合题目要求的.
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A . 3cm, 4cm, 9 cm
B . 8cm, 7cm, 15cm
C . 13cm, 12cm, 20cm
D . 5cm, 5cm, 11cm
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5.
(2023八上·河西期中)
如图,在△ABC中,DE是AC的垂直平分线,AE=3cm,△ABD的周长为13cm,则△ABC的周长为( ).
![](//tikupic.21cnjy.com/2024/02/29/d7/ca/d7ca440ed2ba38eacc53da98f09206ea_147x81.png)
A . 16cm
B . 13cm
C . 10cm
D . 19cm
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A . 50°或80°
B . 80°
C . 150°
D . 70°
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A . SAS
B . ASA
C . AAS
D . SSS
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A . AC=BD
B . ∠C=∠D
C . AD=BC
D . ∠ABD=∠BAC
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A . (m+3, m+1)
B .
C . (m-6, m+1)
D .
二、填空题: 本大题共6小题,每小题3分,共18分.
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14.
(2023八上·河西期中)
如图,
△ABC中,
∠C=90°,
∠BAC的平分线交
BC于点
D , 若
CD=3,则点
D到
AB的距离是
.
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三、解答题:本大题共7小题,共52分.解答应写出文字说明、演算步骤或证明过程.
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17.
(2023八上·河西期中)
如图,点A、B在直线l同侧,请你在直线l上画出一点P,使得PA+PB的值最小,画出图形并保留作图痕迹;
![](//tikupic.21cnjy.com/2024/01/06/50/d6/50d68980af806f38db6f97416e44336b_194x106.png)
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18.
(2023八上·河西期中)
如图,已知三点.
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi%3EA%3C%2Fmi%3E%3Cmfenced%3E%3Cmrow%3E%3Cmo%3E-%3C%2Fmo%3E%3Cmn%3E2%3C%2Fmn%3E%3Cmi%3E%26nbsp%3B%3C%2Fmi%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmi%3E%26nbsp%3B%3C%2Fmi%3E%3Cmn%3E3%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfenced%3E%3Cmo%3E++%EF%BC%8C+%3C%2Fmo%3E%3Cmi%3EB%3C%2Fmi%3E%3Cmfenced%3E%3Cmrow%3E%3Cmn%3E3%3C%2Fmn%3E%3Cmi%3E%26nbsp%3B%3C%2Fmi%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmo%3E-%3C%2Fmo%3E%3Cmn%3E3%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfenced%3E%3Cmo%3E++%EF%BC%8C+%3C%2Fmo%3E%3Cmi%3EC%3C%2Fmi%3E%3Cmfenced%3E%3Cmrow%3E%3Cmo%3E-%3C%2Fmo%3E%3Cmn%3E3%3C%2Fmn%3E%3Cmi%3E%26nbsp%3B%3C%2Fmi%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmi%3E%26nbsp%3B%3C%2Fmi%3E%3Cmi%3E%26nbsp%3B%3C%2Fmi%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfenced%3E%3Cmo%3E++%EF%BC%8C+%3C%2Fmo%3E%3Cmo%3E%E2%96%B3%3C%2Fmo%3E%3Cmi%3EA%3C%2Fmi%3E%3Cmi%3EB%3C%2Fmi%3E%3Cmi%3EC%3C%2Fmi%3E%3C%2Fmath%3E)
与
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmo%3E%E2%96%B3%3C%2Fmo%3E%3Cmsub%3E%3Cmi%3EA%3C%2Fmi%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmsub%3E%3Cmsub%3E%3Cmi%3EB%3C%2Fmi%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmsub%3E%3Cmsub%3E%3Cmi%3EC%3C%2Fmi%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmsub%3E%3C%2Fmath%3E)
关于x轴对称,其中
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmsub%3E%3Cmi%3EA%3C%2Fmi%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmsub%3E%3Cmo%3E++%EF%BC%8C+%3C%2Fmo%3E%3Cmsub%3E%3Cmi%3EB%3C%2Fmi%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmsub%3E%3Cmo%3E++%EF%BC%8C+%3C%2Fmo%3E%3Cmsub%3E%3Cmi%3EC%3C%2Fmi%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmsub%3E%3C%2Fmath%3E)
分别是点A, B, C的对应点. 画出
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmo%3E%E2%96%B3%3C%2Fmo%3E%3Cmsub%3E%3Cmi%3EA%3C%2Fmi%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmsub%3E%3Cmsub%3E%3Cmi%3EB%3C%2Fmi%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmsub%3E%3Cmsub%3E%3Cmi%3EC%3C%2Fmi%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmsub%3E%3Cmo%3E++%EF%BC%8C+%3C%2Fmo%3E%3C%2Fmath%3E)
, 并写出三个顶点
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmsub%3E%3Cmi%3EB%3C%2Fmi%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmsub%3E%3Cmo%3E++%EF%BC%8C+%3C%2Fmo%3E%3Cmsub%3E%3Cmi%3EC%3C%2Fmi%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmsub%3E%3C%2Fmath%3E)
的坐标;
![](//tikupic.21cnjy.com/2024/01/06/9d/12/9d12425143af4f5e924f99784075d8fc_204x203.png)
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(1)
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(2)
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(1)
求证:
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(2)
若点C的坐标为4,0,如图2,点E为AC上一点,且
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi%3E%E2%88%A0%3C%2Fmi%3E%3Cmi%3ED%3C%2Fmi%3E%3Cmi%3EE%3C%2Fmi%3E%3Cmi%3EA%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmi%3E%E2%88%A0%3C%2Fmi%3E%3Cmi%3ED%3C%2Fmi%3E%3Cmi%3EB%3C%2Fmi%3E%3Cmi%3EO%3C%2Fmi%3E%3Cmo%3E++%EF%BC%8C+%3C%2Fmo%3E%3C%2Fmath%3E)
求
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi%3EB%3C%2Fmi%3E%3Cmi%3EC%3C%2Fmi%3E%3Cmo%3E%2B%3C%2Fmo%3E%3Cmi%3EE%3C%2Fmi%3E%3Cmi%3EC%3C%2Fmi%3E%3C%2Fmath%3E)
的长.