How do I figure out the upper and lower bounds for a riemann sum?

This question I'm working on tells me to assume:

Δx=2π/n and x_i=iΔx

and then gives me:

n b
lim ∑ sinx_iΔx = ∫f(x)dx
n⟶∞ i=1 a

Now I'm pretty sure f(x)=sinx, but I don't know how to find a or b. Sorry if this is a little convoluted, it's hard to type it out. Any help here would be appreciated. Thank you

You just have to figure out how many intervals you want to use (n).

Then, as it says, the interval width is Δx=2π/n

The interval is apparently [0,2π]