Question

Verify the identity. cos 4x + cos 2x = 2 - 2 sin^2 2x - 2 sin^2 x

Answer 1

sin (2x + 2x)
sin2x cos 2x + cos2x sin2x
sin2x cos2x + sin2x cos2x
2 sin 2x cos 2x
sin 4x

Answer 2

did you start on the left side?

Answer 3

@PerfectA

Answer 4

No Right

Answer 5

once you get to sin4x idk what to do.

Answer 6

Are you sure you've got the question right?

Answer 7

i plugged in x = 15 degrees and got different values for each side

Answer 8

What?

Answer 9

\[\cos(2x) = 1 - 2\sin^2(x)\]
and
\[\cos(4x) = 1-2\sin^2 (2x)\]
Add them together and you get Right side

Answer 10

AH yes. Sorry, I misread the question.