Results 1 to 4 of 4
Like Tree2Thanks
  • 1 Post By hedi
  • 1 Post By hedi

Math Help - Trigonometric Identity

  1. #1
    Junior Member Greymalkin's Avatar
    Joined
    Jun 2012
    From
    Montreal
    Posts
    74
    Thanks
    1

    Trigonometric Identity

    Prove: cos^2(2x)=\frac{cos4x+1}{2}
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Member
    Joined
    Oct 2012
    From
    israel
    Posts
    103
    Thanks
    14

    Re: Trigonometric Identity

    use the identity for cos(2y) with y=2x.
    Thanks from Greymalkin
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member Greymalkin's Avatar
    Joined
    Jun 2012
    From
    Montreal
    Posts
    74
    Thanks
    1

    Re: Trigonometric Identity

    please elaborate, I dont think my trig book explained double angles beyond the basic identities, all I can think of doing is multiplying double id's together but I dont see how you double a double angle, that is to say make 2x=4x.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Member
    Joined
    Oct 2012
    From
    israel
    Posts
    103
    Thanks
    14

    Re: Trigonometric Identity

    cos(4x)=2cos^2(2x)-1 comes from cos(2x)=2cos^2(x)-1 when substituting 2x for x in the later equation.
    Thanks from Greymalkin
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Trigonometric Identity
    Posted in the Trigonometry Forum
    Replies: 4
    Last Post: March 5th 2012, 09:28 PM
  2. Trigonometric Identity
    Posted in the Trigonometry Forum
    Replies: 0
    Last Post: August 20th 2010, 09:23 PM
  3. Trigonometric identity help
    Posted in the Trigonometry Forum
    Replies: 4
    Last Post: April 1st 2010, 02:35 PM
  4. trigonometric identity
    Posted in the Trigonometry Forum
    Replies: 7
    Last Post: May 19th 2008, 08:18 PM
  5. trigonometric identity
    Posted in the Trigonometry Forum
    Replies: 5
    Last Post: May 5th 2008, 03:42 AM

Search Tags


/mathhelpforum @mathhelpforum