设函数f(x)的导数为f‘(x),且f(x)=f‘(π/2)sinx+cosx,则f'(π/4)=?



f'(x)=f‘(π/2)cosx-sinx
f'(π/2)=f'(π/2)cosπ/2-sinπ/2=-1
f'禒肌操可鬲玖叉雪常磨;(x)=-(sinx+cosx)
f'(π/4)=-根号2


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