简单计算一下即可，答案如图所示
1-sin2x=cosx^2+sinx^2-2sinxcosx=(cosx-sinx)^2√(1-sin2x)=|cosx-sinx|0π/4原积分=∫(0,π/4)cosx-sinxdx+∫(π/4,π/2)sinx-cosxdx=(sinx+cosx)|(0,π/4)+(-cosx-sinx)|(π/4,π/2)=2√2-2
原函数为F(x)=x+½cos2x,结果为F(½π)-F(0)=½π-1
