根据原函数的定义，就是求F（x）=∫f（x）dx∫xsin²xdx=∫x（1-cos2x）/2dx=x²-1/2∫xcos2xdx其中∫xcos2xdx=1/2xsin2x-1/2∫sin2xdx=1/2xsin2x+1/4cos2x+C则原式=x²-1/4xsin2x-1/8cos2x+C
