Answer
$ \sin^{2} x $
Work Step by Step
Given expression is-
$ \frac{\sec^{2} x - 1}{\sec^{2} x} $
= $ \frac{\sec^{2} x }{\sec^{2} x} - \frac{1}{\sec^{2} x} $
= $ 1 - \cos^{2} x $
( cos and sec are reciprocal)
= $ \sin^{2} x $
( From first Pythagorean identity, $1 - \cos^{2}α$ = $\sin^{2}α$)
