If $f'(x) = \tan^{-1}(\sec x + \tan x)$, $-\frac{\pi}{2}<x<\frac{\pi}{2}$ and $f(0) = 0$, then $f(1)$ is
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Trigonometry Tip: The reduction sequence $\sec x + \tan x \rightarrow \frac{1+\sin x}{\cos x} \rightarrow \tan(\frac{\pi}{4} + \frac{x}{2})$ is an extremely common pattern in calculus and should be memorized to save time.