@vv Okey, Thanks. I will try that way. Thanks a lot.

@vv Thanks very much. But the condition given in my materials is the opposite inequality. I devided this integration into [0,\pi/2] and [\pi/2, \pi] and use sinx <=x to figure out if it’s integrable. But my way is wrong. That’s why I try to use maple to see if it is integrable. Do you have some suggestions about this? Thanks very much.

@vv I see. Thanks very much.

@acer Thanks very much. But it still does not work if I get rid of the signs {}. 

@Carl Love Thanks very much. My function is like: