Intersections of Trig Functions with different periods There are 2 trig functions on the same set of axis. 
$f(x)=600\sin(\frac{2\pi}{3}(x-0.25))+1000$
and
$f(x)=600\sin(\frac{2\pi}{7}(x))+500$
How do I go about finding the points of intersections of the two graphs?
Thanks
EDIT: Sorry forgot to mention that this was from a test I had recently and didn't do too well on,so any help would be much appreciated.

you can't set them equal and solve for $x?$
let me try. we need to solve $$600\sin(\frac{2\pi}{3}(x-0.25))+1000 = 600\sin(\frac{2\pi}{7}(x))+500\\
\sin(\frac{2\pi}{3}(x-0.25)) - \sin(\frac{2\pi}{7}(x)) = -\frac56$$
we will make a change of variable $$\frac{2\pi x}{21} = t, x = \frac{21 t}{2\pi} .$$  with that, we have  $$\sin(7t-\pi/6)-\sin(3t)= -\frac56 \tag 1$$ i find that there are eight solutions for $t$ in the interval $0 \le t \le 2\pi$  by looking at the graph of $(1).$
