∵BD为∠abc的平分线,∴∠abd=∠dbc,
∵de为bc垂直平分线,∴e为bc中点,ce=be,
∠dec=90°,∴∠dce=∠dbe,
∴∠acb=∠cbd=∠abd,
∵∠a=90°,∴∠abc=2∠acb=60°
∵ab=3,∴bc=6,
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下面你应该会了吧...