Browse by Stream
QnA
Home
QnA
Go To Your Study Dashboard

Get Answers to all your Questions

header-bg qa
  • Home
  • NCERT
  • Find the principal values of the following: 9. cos inverse of - 1 / root 2

Find the principal values of the following:

    9. \cos^{-1}\left(-\frac{1}{\sqrt2} \right )

Answers (1)

best_answer

Let us assume \cos^{-1}\left(-\frac{1}{\sqrt2} \right ) = x;

Then we have \cos x = \left ( \frac{-1}{\sqrt 2} \right )   

or

   -\cos (\frac{\pi}{4}) = \left ( \frac{-1}{\sqrt 2} \right )  ,

\cos (\pi - \frac{\pi}{4}) = \cos (\frac{3\pi}{4}).

And we know the range of principal values of \cos^{-1} is [0,\pi].

So, the only principal value which satisfies \cos^{-1}\left(-\frac{1}{\sqrt2} \right ) = x is \frac{3\pi}{4}.

Posted by

Divya Prakash Singh

View full answer

Crack CUET with india's "Best Teachers"

  • HD Video Lectures
  • Unlimited Mock Tests
  • Faculty Support
cuet_ads

Similar Questions

Trending Articles/News

anam-khan

CBSE asks schools to ensure error-free LOC forms for Classes 10, 12; edit window from October 13
anam-khan

‘You ruined my career’: Students hit back at CBSE over 'abrupt' removal of additional subjects
anam-khan

‘Careers are at stake’: CBSE removes additional subject option for private students without prior notice

Latest Question