Answer
x
Work Step by Step
Let $\cos ^ {–1} \frac{1}{x} = \theta$, then, $\cos \theta = \frac{1}{x}$
To evaluate, $\sec (\cos ^ {–1} \frac{1}{x}) = \sec\theta$
We know that, $\sec \theta = \frac{1}{\cos \theta}$
Using above relations we get
$\sec \theta = \frac{1}{\frac{1}{x}}$
$=> \sec \theta = x$
