We can divide the quadrant as:
If we have an angle that is 8π/7, we can aproximate 8/7 and see in which quadrant it falls.
As 8/7 is greater than 1 but less than 2, we know that it has to be in the 3rd or 4th quadrant.
As 8/7 is smaller than 3/2, we can conclude it is in the third quadrant.
Answer: the angle 8π/7 is located in the third quadrant.