Question

Verify the identity.

cos 4x + cos 2x = 2 - 2 sin2 2x - 2 sin2 x

Answer 1

Is your equation written as such: cos(4x)+cos(2x)=2-2sin(2x)^2-2sin(x)^2 ?

Answer 2

yes

Answer 3

Do you know the double angle identity for cos(2x)?

Answer 4

\[\cos 4x+\cos 2x=\cos2(2x)+1-2\sin ^{2}x=1-2\sin ^{2}2x+1-2\sin ^{2}x\]

Answer 5

no

Answer 6

\[=2-2\sin ^{2}2x-2\sin ^{2}x\]

Answer 7

Okay, so replace cos(2x) with 1-2sinx^2 and cos(4x) with 1-2sin(2x)^2

Answer 8

ya

Answer 9

Then you have 1-2sin(x)^2+1-2sin(2x)^2=right side.

Answer 10

simplify the variables and you have the left side= to right side.

Answer 11

Shamim is that the answer?

Answer 12

i c

Answer 13

i m happy to solve this problem

Answer 14

ya its my answer

Answer 15

lhs=rhs