Find the angle’s quadrant
Determine the closest x-axis
If the angle is in Quadrant I, the reference angle is the angle itself
If the angle is in Quadrant II, subtract the angle from 180°
If the angle is in Quadrant III, subtract 180° from the angle
If the angle is in Quadrant IV, subtract the angle from 360°
If the angle is negative, add 360° until it is positive, then find the reference angle
If the angle is greater than 360°, subtract 360° until it is between 0° and 360°, then find the reference angle