Results 1 to 5 of 5

Thread: Identities

  1. #1
    Member purplec16's Avatar
    Joined
    Oct 2009
    Posts
    187

    Identities

    Verify that the left side = the right side

    $\displaystyle (sin t+cos t)^2= 1+ sin 2 t$

    $\displaystyle sin^2t + 2 sin t cos t+ cos^2 t = 1+ sin 2 t$

    $\displaystyle 1+ 2sintcost= 1+ sin2t $

    I cant seem to solve the identity
    Last edited by purplec16; Mar 17th 2010 at 06:36 AM. Reason: changed the question
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    Joined
    Jun 2009
    Posts
    806
    Thanks
    4
    sin 2 t cos t
    This should be
    2sint cos t
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member purplec16's Avatar
    Joined
    Oct 2009
    Posts
    187
    Quote Originally Posted by sa-ri-ga-ma View Post
    sin 2 t cos t
    This should be
    2sint cos t
    I changed that, it was a typo
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Member purplec16's Avatar
    Joined
    Oct 2009
    Posts
    187
    Quote Originally Posted by sa-ri-ga-ma View Post
    sin 2 t cos t
    This should be
    2sint cos t
    Do you know how to solve it from there?
    Follow Math Help Forum on Facebook and Google+

  5. #5
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    16,216
    Thanks
    3702
    Quote Originally Posted by purplec16 View Post
    Do you know how to solve it from there?
    $\displaystyle \sin(2t) = 2\sin{t}\cos{t}$ is the well known double angle identity.

    it comes from the sum identity for sine ...

    $\displaystyle \sin(2t) = \sin(t+t) = \sin{t}\cos{t} + \cos{t}\sin{t} = 2\sin{t}\cos{t}$
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 6
    Last Post: Jun 22nd 2010, 11:59 PM
  2. identities..
    Posted in the Trigonometry Forum
    Replies: 3
    Last Post: Jul 29th 2009, 12:33 PM
  3. Identities
    Posted in the Trigonometry Forum
    Replies: 2
    Last Post: Jul 14th 2009, 07:58 AM
  4. identities
    Posted in the Trigonometry Forum
    Replies: 5
    Last Post: Nov 2nd 2008, 03:34 PM
  5. Identities
    Posted in the Trigonometry Forum
    Replies: 3
    Last Post: Jul 11th 2008, 03:53 AM

Search Tags


/mathhelpforum @mathhelpforum