\(\lim _{x \rightarrow 1}\left((1-x) \tan \left(\frac{\pi x}{2}\right)\right)=\)

\(\lim _{x \rightarrow 1}\left((1-x) \tan \left(\frac{\pi x}{2}\right)\right)=\)
  1. \(\frac{1}{\pi}\)
  2. \(\frac{3}{\pi}\)
  3. \(\frac{4}{\pi}\)
  4. \(\frac{2}{\pi}\)

Solution

\(\begin{aligned} & \operatorname{Lim}_{x \rightarrow 1}(1-x) \tan \left(\frac{\pi}{2} x\right) \\ & =\operatorname{Lim}_{x \rightarrow 1} \frac{1-x}{\cot \left(\frac{\pi x}{2}\right)}=\operatorname{Lim}_{x \rightarrow 1} \frac{-1}{-\frac{\pi}{2} \operatorname{cosec}^2\left(\frac{\pi x}{2}\right)} \quad \text{(on applying L'Hospital rule)} \end{aligned}\) \(=\frac{2}{\pi}\) Hence, option (d) is correct.

Asked in: AP EAMCET 2020 (21 Sep Shift 2)

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