令x=sint,则dx=cost dt 则∫√[1-(sint)^2]/sint ·cost dt =∫ cost/sint·cost dt =∫ cott·cost dt =∫ (csct-sint) dt =∫csct dt-∫sint dt =ln|csct-cott|+cost+C =ln|x/[√(1x^2)+1]|+√(1-x^2)+C 注:∫cscxdx=∫1/sinx dx=ln|tanx/2|+C=ln|cscx-cotx|+C