## Need help finding points of inflection

Hi, I'm a little stuck on this problem finding the points of inflection. Here is what I have so far:

fx=2sinx +sin 2x [0, 2pi]

f'x=2cosx+2cos2x

f''x= -2sinx - 4 sin 2x

-2 (sinx + 2sin2x)=0
sinx + 2 (2sinxcosx)=0
...

I get stuck after this. Any help will be appreciated! Thanks.