Разбираемся:
Необходимо найти предел выражения:
\[ \lim_{x \to 1} \frac{1 + \cos(\pi x)}{tg^2(\pi x)} \]Производная числителя:
\[ \frac{d}{dx}(1 + \cos(\pi x)) = -\pi \sin(\pi x) \]Производная знаменателя:
\[ \frac{d}{dx}(tg^2(\pi x)) = 2tg(\pi x) \cdot \frac{1}{\cos^2(\pi x)} \cdot \pi = \frac{2\pi \sin(\pi x)}{\cos^3(\pi x)} \]\[ \lim_{x \to 1} \frac{-\pi \sin(\pi x)}{\frac{2\pi \sin(\pi x)}{\cos^3(\pi x)}} = \lim_{x \to 1} \frac{-\pi \sin(\pi x) \cdot \cos^3(\pi x)}{2\pi \sin(\pi x)} \]
\[ \lim_{x \to 1} \frac{-\cos^3(\pi x)}{2} \]
\[ \frac{-\cos^3(\pi)}{2} = \frac{-(-1)^3}{2} = \frac{-(-1)}{2} = \frac{1}{2} \]
Ответ: \(\frac{1}{2}\)