Evaluate the limit: mathop {lim}limits_{n to | vedclass

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(A) The given limit is of the form $\mathop {\lim}\limits_{n 	o \infty } \frac{1}{n} \sum\limits_{r=0}^{n-1} f\left(\frac{r}{n}ight) = \int\limits_

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(A) The given limit is of the form $\mathop {\lim}\limits_{n 	o \infty } \frac{1}{n} \sum\limits_{r=0}^{n-1} f\left(\frac{r}{n}ight) = \int\limits_0^1 f(x) \, dx$. Here,the expression can be written as $\frac{\pi}{2} \cdot \frac{1}{n} \sum\limits_{r=0}^{n-1} \cos\left(\frac{\pi}{2} \cdot \frac{r}{n}ight)$. Comparing this with the definite integral definition,we have $f(x) = \cos\left(\frac{\pi x}{2}ight)$. Thus,the limit is equal to $\frac{\pi}{2} \int\limits_0^1 \cos\left(\frac{\pi x}{2}ight) \, dx$. Evaluating the integral: $\frac{\pi}{2} \left[ \frac{\sin(\frac{\pi x}{2})}{\frac{\pi}{2}} ight]_0^1 = \left[ \sin\left(\frac{\pi x}{2}ight) ight]_0^1 = \sin\left(\frac{\pi}{2}ight) - \sin(0) = 1 - 0 = 1$.

Evaluate the limit: $\mathop {\lim}\limits_{n \to \infty } \frac{\pi }{2n} \left( 1 + \cos \frac{\pi }{2n} + \cos \frac{2\pi }{2n} + \dots + \cos \frac{(n - 1)\pi }{2n} \right)$

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