# How to find the value of x where 0<=x<=360^@ for sec x= 3.1909?

$\sec x = \frac{1}{\cos} x = 3.1909 \to \cos x = \frac{1}{3.1909} = 0.31$
$\cos x = 0.31 \to x = \pm 71.94 \mathrm{de} g$