Let \( f(x) = \int_{1^{x} \sin^2 \left( \frac{t}{2} \right) dt \). Then the value of \( \lim_{x \to 0} \frac{f(\pi + x) - f(\pi)}{x} \) is equal to:}
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Don't waste time actually integrating the function! Most calculus problems involving a limit of an integral are testing your knowledge of the Fundamental Theorem of Calculus.