# Is this the double limit?

Calculus Level 2

$\large \displaystyle f(n, \theta) = \prod_{r=1}^n \left [1 - \tan^2 \left ( \frac \theta {2^r} \right ) \right]$

Suppose we have a function of $$f(n,\theta)$$ as above, find the value of $$\displaystyle \lim_{\theta\to 0}\lim_{n\to \infty} f(n, \theta)$$.

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