A community for students.
Here's the question you clicked on:
 0 viewing
allison_
 2 years ago
Verify the identity.
cos 4x + cos 2x = 2  2 sin^2 2x  2 sin^2 x
allison_
 2 years ago
Verify the identity. cos 4x + cos 2x = 2  2 sin^2 2x  2 sin^2 x

This Question is Closed

Tushara
 2 years ago
Best ResponseYou've already chosen the best response.1cos(4x)=cos(2x+2x) expand that^

ajprincess
 2 years ago
Best ResponseYou've already chosen the best response.2\(\cos4x=12\sin^2 2x\) \(\cos2x=12\sin^2x\) does that help?

allison_
 2 years ago
Best ResponseYou've already chosen the best response.0It did, but could you please show me how cos 4x = 1  2 sin^2 2x?

ajprincess
 2 years ago
Best ResponseYou've already chosen the best response.2ya sure. \(\cos4x=\cos(2x+2x)\) \(=\cos2x\cos2x\sin2x\sin2x\) \(=\cos^2 2x\sin^2 2x\) \(=1\sin^2 2x\sin^2 2x\) \((\cos^2 2x=1\sin^2 2x)\) \(=12\sin^2 2x\)

allison_
 2 years ago
Best ResponseYou've already chosen the best response.0Do you have a reference where it says cos^2 2x = 1−sin^2 2x? I think it would be useful for me since I have a formula sheet but I don't see that on here...

ajprincess
 2 years ago
Best ResponseYou've already chosen the best response.2\(\cos^2x+\sin^2x=1\) Similarly \(\cos^2 2x+\sin^2 2x=1\) \(\cos^2 2x=1\sin^2 2x\)

allison_
 2 years ago
Best ResponseYou've already chosen the best response.0Thank you for your time and assistance. :)
Ask your own question
Sign UpFind more explanations on OpenStudy
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.