Question

Which expression is equivalent to sec2x − 1?

Answer 1

$sec(2x)-1 \\ \\ \frac{1}{cos(2x)} -1 \\ \\ \frac{1}{1-2 sin^{2}(x) } -1\\ \\ \frac{1}{1-2 sin^{2}(x) } - \frac{1-2 sin^{2}(x) }{1-2 sin^{2}(x) } \\ \\ \frac{2 sin^{2}(x) }{1-2 sin^{2}(x) }$