1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Could you please help me with this question?

  1. Jan 21, 2009 #1
    -10.5 = 3.8 cos [2pi/360(x-172)] this is the question and i am trying to solve for x though i don't know that i can break away the x from cos the way i did... is there another way??
    i don't think the answer should be negative as the question is looking for a day of the year.

    so if i try to solve for x, i end up with

    -2.76 = cos [0.017x - 2.924]

    -1.8876 = cos 0.017x

    -1.8876/0.9999 = x

    x = -1.8878
  2. jcsd
  3. Jan 21, 2009 #2


    User Avatar
    Homework Helper

    There is no solution to the equation.

    Reason is that the cosine of a value ranges between -1 and 1.



    Therefore, to have a real solution for [itex]\theta[/itex], [tex]-1\leq \frac{A}{B}\leq 1[/tex]

    But in the case of your equation:

    [tex]-10.5=3.8cos(\frac{2\pi (x-172)}{360})[/tex]

    [tex]cos(\frac{2\pi (x-172)}{360})=\frac{-10.5}{3.8}[/tex]
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Could you please help me with this question?