积分(0,pie) xsinx/(1+(cosx)^2) dx积分范围为从零到pie.
问题描述：
积分(0,pie) xsinx/(1+(cosx)^2) dx
积分范围为从零到pie.
答
let f(x) = xsinx/(1+(cosx)^2f(-x) = f(x) ie f(x) is even function∫(0,π）xsinx/(1+(cosx)^2) dx = ∫(-π,0）xsinx/(1+(cosx)^2) dxI= ∫(0,π）xsinx/(1+(cosx)^2) dx (1)let y =(π-x)dy = dxx=0,y=πx=π ,...