Question

Can someone tell me how the reference inst the opposite angle?

Answer 1

@zepdrix

Answer 2

What's up? :O
We trying to find reference angle?

Answer 3

Your reference angle can be measured back to the x-axis. So in quadrant 2, your reference will be this large of an angle (the purple).
Algebraically, from quadrant 2, we would do \(\Large\rm 180-105\)