Let $\mathbb{R}$ be the set of all real numbers. Statement I: The function $f : (-1, \frac{1}{2}) \to \mathbb{R}$ defined by $f(x) = \sec x + \tan x$ is a one-one function. Statement II: The function $f : [0, \infty) \to \mathbb{R}$ defined by $f(x) = x^2$ is a one-one function. Which of the above statements is(are) true?