Answer:
[tex]\text{\textit{x}} \ \ = \ \ \displaystyle\frac{\pi}{6} \ \ \ \text{or} \ \ \ \displaystyle\frac{11\pi}{6}[/tex]
Step-by-step explanation:
Given the trigonometric equation
[tex]8 \ \cos{\left(\textit{x}\right)} \ + \ \sqrt{3} \ = \ 5\sqrt{3}[/tex],
hence solving for [tex]\textit{x}[/tex] yields
[tex]8 \ \cos{\left(\textit{x}\right)}\ = \ 5\sqrt{3} \ - \ \sqrt{3} \\ \\ \\ \-\hspace{8px} \cos{\left(x\right)} \ = \ \displaystyle\frac{4\sqrt{3}}{8} \\ \\ \\ \-\hspace{8px} \cos{\left(x\right)} \ = \ \displaystyle\frac{\sqrt{3}}{2} \\ \\ \\ \-\hspace{29px} \textit{x} \ \ \ = \ {\cos}^{-1}\left(\displaystyle\frac{\sqrt{3}}{2}}}\right) \\ \\ \\ \-\hspace{29px} \textit{x} \ \ \ = \ \displaystyle\frac{\pi}{6}[/tex].
Since cosine is positive in both quadrant I and quadrant IV, thus
[tex]\textit{x} \ \ = \ \ 2\pi \ - \ \displaystyle\frac{\pi}{6} \ \ = \ \ \displaystyle\frac{11\pi}{6}[/tex].
Therefore the solutions are
[tex]\textit{x} \ \ = \ \ \displaystyle{\frac{\pi}{6}} \ \ \text{or} \ \ \displaystyle{\frac{11\pi}{6}}[/tex].