y=(sinx)^3y'=3(sinx)^2cosx=(3/2)(1-cos2x)cosx=(3/2)(cosx-cos2xcosx)cos2xcosx积化和差之后按如下规律计算sin(ax)的n阶导数是a^n*sin(ax+(n/2)pi).cos(ax)的n阶导数是a^n*cos(ax+(n/2)pi).pi是圆周率....