通过部分计算解决集成问题。

设arcsinx=u,则x = sinudx = cosuduarc cosx =π/2-arc sinx =π/2-u;代入原公式:

原公式=∫[u(π/2-u)co sudu =(π/2)∫ucosudu-∫u?cosudu=(π/2)∫ud(sinu)-∫u?dsinu

=(π/2)[usinu-∫sinudu]-[u?sinu-2∫usin udu]=(π/2)(usin u+cosu)-u?sinu-2∫ud(cosu)

=(π/2)(usinu+cosu)-u?sinu-2(ucosu-∫cosudu)

=(π/2)(usinu+cosu)-u?西诺-2(ucosu-sinu)+C

=[2+(π/2)u-u?]sinu+[(π/2)-2u]cosu+C

=[2+(π/2)arcsinx-(arcsinx)?]x-[(π/2)-2 arcsinx]cos(arcsinx)+C

=[2+(π/2)arcsinx-(arcsinx)?]x-[(π/2)-2arcsinx]√(1-x?)+C,C是常数。