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MHT CET · Maths · Inverse Trigonometric Functions

\(\cot ^{-1}\left(2 \cdot 1^2\right)+\cot ^{-1}\left(2 \cdot 2^2\right)+\cot ^{-1}\left(2 \cdot 3^2\right)+\ldots \ldots \ldots \ldots \ldots \ldots \ldots \infty =\)

  1. A \(\frac{\pi}{2}\)
  2. B \(\frac{\pi}{3}\)
  3. C \(\frac{\pi}{4}\)
  4. D \(\overline{8}\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(\frac{\pi}{4}\)

Step-by-step Solution

Detailed explanation

\(\sum_{n=1}^{\infty} \cot^{-1}(2n^2) = \sum_{n=1}^{\infty} \tan^{-1}\left(\frac{1}{2n^2}\right)\) \(= \sum_{n=1}^{\infty} \tan^{-1}\left(\frac{2}{4n^2}\right)\)