Hello all, I want to prove the following inequality. sin(x)<x for all x>0. Now I figured that I put a function f(x)=x-sin(x), and show that it is increasing for all x>0. But this alone doesn't prove it. I need to show we have inequality from the start. I can't show that lim f(x) as x->0 is positive cause this limit equals 0. I can show that we have equality at x=0, and only at x=0. Therefore, sin(x) <=x for all x>=0, and we only have equality at x=0. So sin(x)<x for all x>0. This doesn't seem the right way to do it though. Thanks.