Results 1 to 3 of 3

Math Help - Need help inputting law of cosines on ti83+

  1. #1
    Newbie
    Joined
    Feb 2009
    Posts
    9

    Need help inputting law of cosines on ti83+

    Solve:




    Ok, so I use the law of cosines, correct?

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

    Now, when I input this into my ti83+:

    2017^2+2938^2-2506^2/2(2017x2938)

    I get -1.86075644e13

    So, next I am supposed to multiply by the inverse cosine, right? But -1.8 is obviously not right, so what am I doing wrong?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    11,621
    Thanks
    426
    Quote Originally Posted by coasterguy View Post
    Solve:




    Ok, so I use the law of cosines, correct?

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

    Now, when I input this into my ti83+:

    2017^2+2938^2-2506^2/2(2017x2938)

    I get -1.86075644e13

    So, next I am supposed to multiply by the inverse cosine, right? But -1.8 is obviously not right, so what am I doing wrong?
    check that your calculator is in degree mode. here's how it should look on your home screen ...
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Feb 2009
    Posts
    9
    Quote Originally Posted by skeeter View Post
    check that your calculator is in degree mode. here's how it should look on your home screen ...

    Thank you!
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 0
    Last Post: September 29th 2009, 11:35 AM
  2. Ti83 program for quadratic polynomials?
    Posted in the Calculators Forum
    Replies: 1
    Last Post: July 2nd 2009, 09:28 PM
  3. input log into TI83
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: October 21st 2008, 07:25 PM
  4. TI83 graphing table help!
    Posted in the Algebra Forum
    Replies: 1
    Last Post: December 17th 2007, 08:38 PM
  5. The Law of Cosines
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: April 28th 2005, 11:29 AM

Search Tags


/mathhelpforum @mathhelpforum