Yes you need to draw a reference angle.
I will write t instead of theta.
You are told that that 5pi/2 < t <3pi. Both 5pi/2 = 2 1/2 pi and 3 pi are larger than 2 pi. You can always add to subtract 2pi to an angle without changing the location of the angle. A big hint is to subtract 2pi from both 5pi/2 and 3pi. This will give you an angle between 0pi and 2pi.
Of course, if you prefer, you can change the given angles into degrees and do exactly what I suggested above.
Please give it a try and post back with your work including a diagram.