Answer:
120° and 240°
Step-by-step explanation:
The given info about the angle x is cos x = - 1/2.
By definition, cos x = - 1/2 = (adjacent side) / hypotenuse, so here we can assume the adjacent side is -1 and the hypotenuse is 2.
A negative cosine tells us that the angle is in Quadrant II or Quadrant III.
If x is in Quadrant II, then its value is 120°
If x is in Quadrant III, then its value is 120° + 120°, or 240°
Check:
