How do you determine the quadrant in which #-pi/12# lies?
First off we know there are 4 quadrants and rotation starts from the positive x-axis. Positive rotation moves counter-clockwise up towards the positive y-axis and negative rotation moves clockwise down towards the negative y-axis. The diagram below shows positive rotation (negative rotation goes in the opposite direction).
We have negative rotation, so we move clockwise, downwards towards the negative y-axis.
How far do we move in that direction?
The negative y-axis is at