Answer
$\frac{\pi }{4}$ is the solution of the given equation.
Work Step by Step
We know that according to the ratio table of trigonometry, the value of $\cos \frac{\pi }{4}$ is provided as $\frac{\sqrt{2}}{2}$.
$\begin{align}
& \cos x=\frac{\sqrt{2}}{2} \\
& \cos \frac{\pi }{4}=\frac{\sqrt{2}}{2} \\
& \frac{\sqrt{2}}{2}=\frac{\sqrt{2}}{2}
\end{align}$
Thus, $\cos x=\frac{\sqrt{2}}{2}$ is true.
