Answer
$\sec\theta$ = $ \frac{1}{\sqrt (1-\sin^{2}\theta)}$
Work Step by Step
We know that $\sec\theta$ and $\cos\theta$ are reciprocal to each other-
Therefore-
$\sec\theta\times\cos\theta$ = 1
or $\sec\theta$ = $ \frac{1}{\cos\theta}$
or $\sec\theta$ = $ \frac{1}{\sqrt (1-\sin^{2}\theta)}$
[From Pythagorean identity, $\cos\theta$ can be written as $\sqrt (1-\sin^{2}\theta)$]
