答：
(π/2→π) ∫ [ (sinx) /x ]' dx
=(π/2→π) ∫ d [ (sinx) / x ]
=(π/2→π) [(sinx)/x]
=0-1/(π/2)
=-2/π
∫上π 下π/2 {sin x/x} ′ dx等于多少
答：
(π/2→π) ∫ [ (sinx) /x ]' dx
=(π/2→π) ∫ d [ (sinx) / x ]
=(π/2→π) [(sinx)/x]
=0-1/(π/2)
=-2/π