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COMEDK · Maths · 23. Inverse Trigonometric Functions

\(\cot ^{-1}(21)+\cot ^{-1}(13)+\cot ^{-1}(-8)=\)

  1. A 0
  2. B \(\cot ^{-1} 26\)
  3. C \(\pi\)
  4. D None of these
Verified Solution

Answer & Solution

Correct Answer

(C) \(\pi\)

Step-by-step Solution

Detailed explanation

We have, \(\cot ^{-1}(21)+\cot ^{-1}(13)+\cot ^{-1}(-8)\) \(=\tan ^{-1}\left(\frac{1}{21}\right)+\tan ^{-1}\left(\frac{1}{13}\right)+\cot ^{-1}(-8)\) \(=\tan ^{-1}\left(\frac{\frac{1}{21}+\frac{1}{13}}{1-\frac{1}{21} \times \frac{1}{13}}\right)+\cot ^{-1}(-8)\)…