Inverse Trigonometric Functions Question 210
Question: $ {{\cos }^{-1}}( \cos \frac{7\pi }{6} )= $
Options:
A) $ \frac{7\pi }{6} $
B) $ \frac{5\pi }{6} $
C) $ \frac{\pi }{6} $
D) None of these
Show Answer
Answer:
Correct Answer: B
Solution:
$ {{\cos }^{-1}}( \cos \frac{7\pi }{6} )={{\cos }^{-1}}{ \cos ( \pi +\frac{\pi }{6} ) } $ = $ {{\cos }^{-1}}( -\cos \frac{\pi }{6} )=\pi -{{\cos }^{-1}}\cos \frac{\pi }{6}=\pi -\frac{\pi }{6}=\frac{5\pi }{6} $ .
BETA
