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!

Prove cosign problem

  1. Sep 3, 2008 #1
    1. The problem statement, all variables and given/known data
    Prove that:
    [tex]\sqrt{3}cos 20 - sec 40=4[/tex]


    3. The attempt at a solution
    Assuming th statement to be true;
    [tex]\sqrt{3}cos 20 - \frac{1}{2cos^{2}20 - 1}=4[/tex]

    [tex]2\sqrt{3}cos^{3} 20- 8 cos^{2} 20 -\sqrt{3}cos 20+3=0[/tex]

    It results in a cubic equation???? Help
     
  2. jcsd
  3. Sep 3, 2008 #2

    Defennder

    User Avatar
    Homework Helper

    Re: Trigonometry

    Problem with this question is that it's not even true for both radians and degrees. Try it on your calc.
     
  4. Sep 3, 2008 #3

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    Re: Trigonometry

    That is an excellent point. I hadn't even thought to try it. Duh.
     
  5. Sep 4, 2008 #4
    Re: Trigonometry

    Sorry guys it was a type error!
     
  6. Sep 4, 2008 #5
    Re: Trigonometry

    Eh, if that 0 was a theta, it looks solvable.
     
  7. Sep 5, 2008 #6

    Defennder

    User Avatar
    Homework Helper

    Re: Trigonometry

    Yeah, but it reads "prove that..." and not "solve..."
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Prove cosign problem
  1. Prove problem help (Replies: 7)

Loading...