Which of the following could be the measure of the angle below? 
-180°, -120°, 140°, 510°

Solution:

If the angle is measured counter clockwise, the sign is positive

So the angle could be

180°,

180° + 360° = 540°,

180° + 2(360)° = 180° + 720° = 900°, ….

If the angle is measured clockwise, the sign is negative

So the angle could be

-180°,

-180° - 360° = -540°, 

-180° - 2(360°) = -180° - 720° = -900°….

Therefore, the measure of the angle is -180°.

Which of the following could be the measure of the angle below?

Summary:

The measure of the angle is -180°.