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MHT CET · Maths · Inverse Trigonometric Functions

The value of \(\cos ^{-1}\left(\cos \frac{8 \pi}{3}\right)\) is

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

Answer & Solution

Correct Answer

(C) \(\frac{2 \pi}{3}\)

Step-by-step Solution

Detailed explanation

\(\cos \frac{8 \pi}{3} = \cos \left(2\pi + \frac{2\pi}{3}\right) = \cos \frac{2\pi}{3}\) \(\cos ^{-1}\left(\cos \frac{8 \pi}{3}\right) = \cos ^{-1}\left(\cos \frac{2\pi}{3}\right) = \frac{2\pi}{3}\)