∫(0->1) x.arctanx dx=(1/2)∫(0->1) arctanx dx^2=(1/2) [x^2.arctanx]|(0->1) -(1/2)∫(0->1) x^2/(1+x^2) dx= π/8 -(1/2)∫(0->1) [1- 1/(1+x^2)] dx=π/8 -(1/2) [x- arctanx] |(0->1)=π/8 -(1/2) (1- π/4)=π/4 -1/2
