Question

Find three angles, two positive and one negative, that are coterminal with the given angle: −5π18.
a.−13π18,13π18,31π18
b.−41π18,31π18,67π18
c.−23π18,13π18,31π18
d.−23π18,31π18,67π18
e.−41π18,13π18,67π18 f) none of the above.

Answer 1

one would be   2pi - 5pi/18 = 31pi/18
another positive one is 31pi/18 + 36pi/18  = 67pi/18
and the negative angle is -5pi/18 - 36pi/18  = -41pi/18

The answer is  b