Browse by Stream
QnA
Home
QnA
Go To Your Study Dashboard

Get Answers to all your Questions

header-bg qa
  • Home
  • NCERT
  • Find the general solution for each of the following equation cos 4x = cos 2x

Find the general solution for each of the following equation 

Q (5)  \small \cos 4x = \cos 2x

Answers (1)

cos4x = cos2x
cos4x - cos2x = 0
We know that
\cos A - \cos B = -2\sin\frac{A+B}{2}\sin\frac{A-B}{2}
We use this identity
\therefore  cos 4x - cos 2x  = -2sin3xsinx
\Rightarrow -2sin3xsinx = 0    \Rightarrow   sin3xsinx=0
So, by this we can that either 
sin3x = 0     or    sinx = 0
3x = n\pi                 x = n\pi
  x = \frac{n\pi}{3}                x = n\pi 

Therefore, the general solution is

 x=\frac{n\pi}{3}\ or\ n\pi \ where \ n\in Z   

Posted by

Safeer PP

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 board exams 2025 from February 15; Class 10, 12 subject-wise marks distribution
anam-khan

CBSE Date Sheet 2025: Class 10, 12 board exam dates soon on cbse.gov.in; previous trends, sample papers
anam-khan

CBSE Board Exams 2025: 75% attendance must for students to be eligible, reiterates board

Latest Question