Question

find the general solution of the equation cos 3x = cos 2x​

Answer 1

$cos(3x) = cos(2x) \\ 3x = 2n\pi + 2x \\ 3x - 2x = 2n\pi \\ x = 2n\pi$

$cos(3x) = cos(2x) \\ 3x = 2n\pi - 2x \\ 3x + 2x = 2n\pi \\ 5x = 2n\pi \\ x=2n\pi/5$

it is having two aspects,I.e., + and -

Answer 2

Answer:

general formula x=2npi or x=2npi/5

Step-by-step explanation:

coss3x=cos2x

cos2x-cos3x=0

2sin(3x-2x/2)sin(3x+2x/2)=0

2sin(x/2)sin(5x/2)=0

let sin(x/2)=0

x/2=npi

x=2npi

now let us consider sin(5x/2)=0

5x/2=npi

5x=2npi

x=2npi/5