Results 1 to 2 of 2

Math Help - Sum of squares of cosine.

  1. #1
    arm
    arm is offline
    Newbie
    Joined
    Feb 2011
    Posts
    14

    Sum of squares of cosine.

    Find: cos ^{2}(\frac{\pi }{5})+ cos^{2} (\frac{2\pi }{15})+ cos^{2} (\frac{8\pi }{15})
    Last edited by mr fantastic; February 26th 2011 at 12:56 PM. Reason: Re-titled.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by arm View Post
    Find: cos ^{2}(\frac{\pi }{5})+ cos^{2} (\frac{2\pi }{15})+ cos^{2} (\frac{8\pi }{15})
    To get help you need to show some effort. Show your work and say where you're stuck.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 1
    Last Post: June 22nd 2011, 12:43 PM
  2. Magic squares of Squares
    Posted in the Math Puzzles Forum
    Replies: 5
    Last Post: September 22nd 2010, 09:58 AM
  3. Why is cosine(-x) equal to cosine(x)?
    Posted in the Trigonometry Forum
    Replies: 4
    Last Post: August 6th 2010, 05:56 PM
  4. Replies: 4
    Last Post: November 13th 2009, 05:12 PM
  5. Law of cosine
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: July 12th 2009, 03:20 PM

Search Tags


/mathhelpforum @mathhelpforum