i) the least positive coterminal angle can be found by subtracting 2pi from your original angle. We subtract 2pi because 11pi/3 is larger than 2pi.
So: 11pi/3 - 2pi = 11pi/3 - 6pi/3 = 5pi/3 or
ii) The reference angle is the smallest angle you can make with the x-axis. Since 5pi/3 is in Quadrant IV, the reference angle is found by:
2pi - 5pi/3 = 6pi/3 - 5pi/3 = pi/3 or
iii) 5pi/3 or 300 degrees is found in Quadrant IV.