∫dx/[x+√(1-x^2)] 令x=sint原式=∫cost/(sint+cost) dt=1/2 ∫(cost-sint)/(sint+cost) dt+1/2 ∫(cost+sint)/(sint+cost) dt=1/2∫1/(sint+cost) d(sint+cost)+1/2∫dt=1/2ln|sint+cost|+1/2t+ct=arcsinxcost=√1-x^2所以原式=1/2ln|x+√(1-x^2)|+1/2arcsinx+C