Answer:
x = 60°, 120°
Step-by-step explanation:
If we let [tex]t=2x[/tex], our equation now becomes [tex]\cos{t}=-1/2[/tex], which is true for two values of t: 120° and 240°. Since t = 2x, we can say that [tex]120^{\circ}=2x[/tex] and [tex]240^{\circ}=2x[/tex], and therefore [tex]x = 60^{\circ}[/tex] and [tex]x=120^{\circ}[/tex]
