What is a reference triangle and how does it help you work
with angles on the unit circle?

A triangle relative to which trilinear coordinates

When you see a trig equation that asks you to solve for an unknown angle, you move backward from what you’re given to arrive at a solution that makes sense. This solution should be in the form of an angle measurement, and the location of the angle should be in the correct quadrant. Knowledge of the unit circle comes in handy here because you’ll be thinking of angles that fulfill the requirements of the given equation.

-Hops