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下列命题中,真命题是( ) A.等腰梯形是中心对称图形 B.对角线相等且互相垂直...
下列命题中,真命题是( )
A.等腰梯形是中心对称图形
B.对角线相等且互相垂直的四边形是菱形
C.相等的圆心角所对的弦相等
D.相似三角形周长的比等于对应中线的比
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如图,
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≤s≤
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<s≤
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≤s≤
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D.
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<s<
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