I need help finding the critical points of this function: $f(x)=x-2 \sin x $
I found $f'(x)=1-2 \cos x $ and $f''(x)=2\sin x$
I know the next step is to set $f'(x)=0$ but when I do that I get $x=1.047$. But looking at the graph I see there is another critical point. How do I obtain this other point?
I also need to find the regions where the graph is concave upward and concave downward.