Thanks to all of you who support me on Patreon. You da real mvps! $1 per month helps!! 🙂 https://www.patreon.com/patrickjmt !! Evaluating Trigonometric Functions Using the Reference Angle, Example 1. In this video, I do a quick review of the unit circle in quadrant 1 and discuss how to use the reference angle to evaluate some trig functions.