Hello!
[tex]\large\boxed{\frac{2\pi}{3} \text{ and } \frac{4\pi}{3}}[/tex]
2cosФ + 1 = 0
Begin by isolating for cosФ. Subtract both sides by -1:
2cosФ = -1
Divide both sides by 2:
cosФ = -1/2
Using the unit circle, we know that from [0, 2π), values that have a cosine of -1/2 are 2π/3 and 4π/3.
Therefore, the solutions of this equation are:
Ф = 2π/3 and 4π/3
