A reference angle is the angle closest to the x-axis from the given angle.
Also called t-bar, a t with a bar over it. Reference angles are always POSITIVE.
Theta = 300, you can continue around to 360, or go back to 180. Going to 360 would be 60 degrees and going back to 180 would be 120 degrees. Therefore, the reference angle would be 60 degrees.
Theta = 225: 360 - 225 = 135; 225-180 = 45; t-bar = 45 degrees
Theta = 480; This angle has already made a full revolution (360) and is on the second revolution. It is coterminal to 120 degrees. 180-120 = 60 degrees;
120-0 = 120 degrees. t-bar = 60 degrees.
Theta = -210. -120 just means you are moving clockwise instead of counterclockwise.
180-120 = 60 degrees; 120- 0 = 120 degrees; t-bar = 60 degrees
