Reference angle:
1st quadrant (0° to 90°) : only the angle
2nd quadrant (90° to 180°) : 180° - angle
3rd quadrant (180° to 270°) : angle - 180°
4th quadrant (270° to 360°) : 360° - angle
Example:
1) 152°
This angle lies in second quadrant.
So reference angle: 180° - 152° = 28°
2) 300°
This angle lies in fourth quadrant.
So reference angle: 360° - 300° = 60°
3) 192°
This angle lies in third quadrant.
So reference angle: 192° - 180° = 12°
