Name a positive and a negative angle coterminal with the angle 4π /3

Answer 1

To find coterminal angles, add/subtract multiples of 2pi ( remember that rotating 2pi radians is one complete revolution of a circle, so you end up back at the point you started from):

4pi/3 + 2pi = 4pi/3+ 6pi/3 = 10pi/3

4pi/3 - 2pi = 4pi/3 - 6pi/3 = -2pi/3

There are infinitely many other choices that will work, found by adding/subtracting other multiples of 2pi.