Question

Can anyone help me with this? Please.

Verify the identity.

cos 4x + cos 2x = 2 – 2 sin^2 2x – 2 sin^2 x

Answer 1

What do you mean, verify the identity? Can you give an example? :)

Answer 2

Like, I have to verify that cos 4x + cos 2x is equal to 2-2sin^2 2x-2 sin^2 x.

In my notes it says things like sin^2u+cos^2u=1, sin u=1/csc u, etc. I get the concept, but I dont really understand how to apply it. :(

Answer 3

@amoodarya Can you help, please? :o)

Answer 4

do you know half angle formulas?

Answer 5

No :/

Answer 6

do you know this
cos (a+b)=cos a cos b -sin a sin b ?