JEE Advance - Mathematics (1994 - No. 17)
Let $$0 < x < {\pi \over 4}$$ then $$\left( {\sec 2x - \tan 2x} \right)$$ equals
$$\tan \left[ {x - {\pi \over 4}} \right]$$
$$\tan \left[ {{\pi \over 4} - x} \right]$$
$$\tan \left[ {x + {\pi \over 4}} \right]$$
$${\tan ^2}\left[ {x + {\pi \over 4}} \right]$$