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COMEDK · Maths · 23. Inverse Trigonometric Functions

The value of the expression \(\cos^{-1}\left(\cos\dfrac{7\pi}{6}\right) + \sin^{-1}\left(\sin\dfrac{22\pi}{3}\right) + \tan^{-1}\left(\tan\dfrac{4\pi}{5}\right)\) is:

  1. A \(\dfrac{7\pi}{10}\)
  2. B \(-\dfrac{11\pi}{30}\)
  3. C \(\dfrac{3\pi}{10}\)
  4. D \(\dfrac{29\pi}{30}\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(\dfrac{3\pi}{10}\)

Step-by-step Solution

Detailed explanation

The principal value branch of \(\cos^{-1}x\) is \([0, \pi]\). \(\cos^{-1}\left(\cos\dfrac{7\pi}{6}\right) = \cos^{-1}\left(\cos\left(2\pi - \dfrac{5\pi}{6}\right)\right) = \cos^{-1}\left(\cos\dfrac{5\pi}{6}\right) = \dfrac{5\pi}{6}\) The principal value branch of \(\sin^{-1}x\)…