设f（x）=sinxcosx，那么f′（x）=

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SQL Error: select id,body,options from ***_enewstiku_ where sourceid='19254' and id < 1663718 and id<>'1663718' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='19254' and id > 1663718 and id<>'1663718' order by id asc limit 5