There are two main ways to label angles: 1. give the angle a name, usually a lower-case letter like a or b, or sometimes a Greek letter like α (alpha) or θ (theta) Trigonometric ratios of 180 degree minus theta. Earth completes one full rotation each day making the sun appear to rise and set. Trigonometric ratios of angles greater than or equal to 360 degree. –270° Some angles have special names: an angle of 180° is called a straight angle, and an angle of 90° is called a right angle. The larger angle at the intersection of a vertical and a horizontal line creates a 270 degree angle. An angle which is 180 degree is - straight angle.An angle between 180 and 270 degree is called reflex angle.An angle which is 360 degree is - complete angle."}} A straight line creates a 180 degree angle.