## Algebra and Trigonometry 10th Edition

$θ=\frac{\pi}{3}+2n\pi$ and $θ=\frac{5\pi}{3}+2n\pi$, where $n$ is an integer.
$4~cos~θ=1+2~cos~θ$ $2~cos~θ=1$ $cos~θ=\frac{1}{2}$ The period of $cos~θ$ is $2\pi$. The solutions in the interval: $[0,2\pi)$ are: $θ=\frac{\pi}{3}$ and $θ=\frac{5\pi}{3}$ Now, add multiples of $2\pi$ to each of the solutions: $θ=\frac{\pi}{3}+2n\pi$ and $θ=\frac{5\pi}{3}+2n\pi$, where $n$ is an integer.