Results 1 to 2 of 2

Math Help - Proof question

  1. #1
    ctt
    ctt is offline
    Newbie
    Joined
    Nov 2008
    Posts
    1

    Proof question

    How can I prove 4(sin^4 x+ cos^4 x) always equals cos 4x + 3?

    I don't think I've been taught the identities that I need...

    Thanks in advance
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor Mathstud28's Avatar
    Joined
    Mar 2008
    From
    Pennsylvania
    Posts
    3,641
    Quote Originally Posted by ctt View Post
    How can I prove 4(sin^4 x+ cos^4 x) always equals cos 4x + 3?

    I don't think I've been taught the identities that I need...

    Thanks in advance
    Yeah, maybe not, its ugly but this one is most directly solved with

    \cos(x)=\frac{e^{ix}+e^{-ix}}{2}

    and

    \sin(x)=\frac{e^{ix}-e^{-ix}}{2i}
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Proof question
    Posted in the Discrete Math Forum
    Replies: 4
    Last Post: January 21st 2010, 08:31 AM
  2. proof question 2,1
    Posted in the Differential Geometry Forum
    Replies: 5
    Last Post: October 26th 2009, 03:54 PM
  3. a proof question..
    Posted in the Algebra Forum
    Replies: 4
    Last Post: November 25th 2008, 09:35 AM
  4. Proof Question
    Posted in the Algebra Forum
    Replies: 2
    Last Post: March 19th 2006, 06:54 AM
  5. Proof question
    Posted in the Algebra Forum
    Replies: 4
    Last Post: February 22nd 2006, 03:50 PM

Search Tags


/mathhelpforum @mathhelpforum