Results 1 to 4 of 4

Math Help - simplifying

  1. #1
    Junior Member
    Joined
    Aug 2009
    Posts
    31

    Unhappy simplifying

    I was wondering if someone could help me with this question.. i have absolutely no idea on how to answer it..

    2sin(4x)cos(4x)cos(7x)-(cos^2(4x)-sin^2(4x))sin(7x)

    please show steps..
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Oct 2005
    From
    Earth
    Posts
    1,599
    Quote Originally Posted by fvaras89 View Post
    I was wondering if someone could help me with this question.. i have absolutely no idea on how to answer it..

    2sin(4x)cos(4x)cos(7x)-(cos^2(4x)-sin^2(4x))sin(7x)

    please show steps..
    2sin(4x)cos(4x)=sin(8x) and cos^2(4x)-sin^2(4x)=cos(8x)

    That should get you through most of the problem.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    Aug 2009
    Posts
    31
    okay so from your help

    i got sin(8x)cos(7x)-cos(8x)sin(7x)

    do i simply just minus eachother or times.. im not too sure what to do next..
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    Joined
    Oct 2005
    From
    Earth
    Posts
    1,599
    You need to review common trig identities thoroughly. I don't mean that as an insult but as advice. Take a look at sum and difference formulas for sin and cos and double angle formulas.

    sin(a-b)=sin(a)cos(b)-sin(b)cos(a)

    That is the identity you need to finish.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. simplifying help...
    Posted in the Algebra Forum
    Replies: 1
    Last Post: May 21st 2010, 06:17 PM
  2. Simplifying
    Posted in the Trigonometry Forum
    Replies: 7
    Last Post: January 9th 2010, 07:12 PM
  3. More simplifying help.
    Posted in the Algebra Forum
    Replies: 3
    Last Post: September 17th 2009, 12:44 AM
  4. need help simplifying
    Posted in the Algebra Forum
    Replies: 2
    Last Post: February 5th 2009, 09:06 AM
  5. Simplifying!
    Posted in the Algebra Forum
    Replies: 1
    Last Post: February 25th 2008, 10:48 AM

Search Tags


/mathhelpforum @mathhelpforum