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下列命题中,为真命题的是( ) A.长度相等的弧所对的圆心角相等 B.垂直于圆的...
下列命题中,为真命题的是( )
A.长度相等的弧所对的圆心角相等
B.垂直于圆的半径的直线是该圆的切线
C.过弦的中点的直线必过圆心
D.三角形的外心到三个顶点的距离相等
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一等腰直角三角形的内切圆与外接圆的半径之比为( )
A.
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B.
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C.
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D.
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下列说法中,正确的是( )
A.垂直于半径的直线一定是这个圆的切线
B.任何三角形有且只有一个内切圆
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D.三角形的内心到三角形的三个顶点的距离相等
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今有一副三角板如图,中间各有一个直径为2cm的圆洞,现用三角板a的30°角那一头插入三角板b的圆洞中,则三角板a通过三角板b的圆洞那一部分的最大面积为( )cm
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A.
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D.
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