积分:根号(1-x^2)dx 令x=sint 则dx=costdt =积分:根号(1-(sint)^2)costdt =积分:(cost)^2dt =积分;(1+cos2t)/2dt =t/2+sin2t+C t=arcsinx代入有: =arcsinx/2+x(1-x^2)^(1/2) /2 +C
