Answer
$2$
Work Step by Step
$\lim_{\theta\to\pi/4}\frac{tan\theta-1}{\theta-\pi/4}=\lim_{\theta\to\pi/4}\frac{tan\theta-tan(\pi/4)}{\theta-\pi/4}=(tan\theta)'|_{\theta=\pi/4}=(sec^2\theta)|_{\theta=\pi/4}=sec^2(\pi/4)=2$
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