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7.(3分)(2012 宁夏)如图,AB为⊙O的直径,PD切⊙O于点C,交AB的延长线于D,且CO=CD,则∠PCA=( )
7.(3分)(2012 宁夏)如图,AB为⊙O的直径,PD切⊙O于点C,交AB的延,2012-2013学年安徽省合肥市蜀山区九年级(上)期末数学试卷(6)">
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7.(3分)(2012 宁夏)如图,AB为⊙O的直径,PD切⊙O于点C,交AB的延长线于D,且CO=CD,则∠PCA=( )