F(x)=∫ydx＝∫√(1-x^2)dx令x=sint,则√(1-x^2)=cost,dx=costdt,从而∫√(1-x^2)dx=∫cost^2dt=∫[(1+cos2t)/2]dt=∫(1/2)dt+∫[(cos2t)/2]dt=t/2+(sin2t)/4+c=t/2+sint*cost/2+c=(arcsinx)/2+[x*√(1-x^2)]/2+c...