Find the reference angle θ'.

Question

θ= -7pi/9

Answer 1

-7pi/9 + 2pi = 11pi/9
This is in QII, so we need to subtract it from pi:

pi - 11pi/9 = 7pi/9

You can also subtract 2pi if the angle is large and positive.

Answer 2

Oops. 11pi/9 > pi, so subtract pi to get
2pi/9

play around adding and subtracting 2pi or pi till you get an angle in QI.