∫arctan(t)dt=tarctant-∫td(arctant)=tarctant-∫t/(1+t^2)dt=tarctant-∫t/(1+t^2)dt=tarctant-(1/2)×∫d(1+t^2)/(1+t^2)=tarctant-(1/2)ln(1+t^2)(0,x)∫arctan(t)dt=(0,x)[tarctant-(1/2)ln(1+t^2)]=xarctanx-...