Results 1 to 2 of 2

Math Help - triangle give 2sides and a angle -cosine?

  1. #1
    Member
    Joined
    Jun 2008
    Posts
    175

    triangle give 2sides and a angle -cosine?

    Hi could someone please help me with this thankyou.

    Craka_photo/math - Photobucket - Video and Image Hosting

    give triangle ABC with a=7 b=x c=5 and angle A = 60 degrees. Find x
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor red_dog's Avatar
    Joined
    Jun 2007
    From
    Medgidia, Romania
    Posts
    1,252
    Thanks
    5
    Apply the cosine rule:

    a^2=b^2+c^2-2bc\cos A

    Then, 49=x^2+25-5x\Rightarrow x^2-5x-24=0

    Find the roots and choose the positive one.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 1
    Last Post: April 4th 2011, 11:36 AM
  2. cosine of a double angle
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: April 22nd 2009, 03:00 PM
  3. find values of sine, cosine etc of angle
    Posted in the Algebra Forum
    Replies: 1
    Last Post: March 17th 2009, 01:14 AM
  4. Cosine of an Angle
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: November 10th 2008, 03:21 AM
  5. Replies: 27
    Last Post: April 27th 2008, 10:36 AM

Search Tags


/mathhelpforum @mathhelpforum