+1632 Coterminal angles means the same angle, just you rotated the terminal-line around the unit circle a multitude of times. Thus, all coterminal angles of 2pi/3 are in the form 2pi/3 + 2(k)pi, k is in the realm of integers: 2pi/3 - 4pi = -10pi/3, 2pi/3 - 2pi = -4pi/3, 2pi/3 + 2pi = 8pi/3, thus the FIRST, SECOND, and LAST are the only correct answers.
