如图等腰△ABC，AB=AC，AB为直径作⊙O交AC、BC于D、E，过B切线交OE延长线于F．

选A
∵OE=OB
所以∠OEB=∠OBE
∵AB=AC
所以∠ACB=∠OBE
所以∠OEB=∠ACB
所以OF‖CD
延长OF交⊙O于G
∵FG‖AC
所以⌒DE=⌒AG
⌒AG=⌒BE

所以⌒DE=⌒AG

hgggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggg

选D 做辅助线，链接OD.BD，用三角形相似，对应边成比例证明，要注意圆的半径都是相等的，注意转化相等线段

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