Question

1 + sec2x sin2x = sec2x

Answer 1

\[1+\sec(2x)\sin(2x)=\sec(2x)\\
1+\tan(2x)=\sec(2x)\]

And you know that: \[1+\tan^2(2x)=\sec^2(2x)\]

You got it :p

Answer 2

yes thanks