∫dx/(1+√(1-x^2))x=sinu dx=cosudu √(1-x^2)=cosutan(u/2)=sinu/(1+cosu)=x/(1+√(1-x^2))=∫cosudu/(1+cosu)=∫[1-1/(1+cosu)]du=u-∫du/(1+cosu)=u-∫d(u/2)/(cos(u/2))^2=u-tan(u/2)+C=arcsinx - x/(1+√(1-x^2)) +C
