已知b>0，直线与直线互相垂直，则ab的最小值等于

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SQL Error: select id,body,options from ***_enewstiku_ where sourceid='15531' and id < 2638696 and id<>'2638696' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='15531' and id > 2638696 and id<>'2638696' order by id asc limit 5