1. Limited time only! Sign up for a free 30min personal 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!

Trig problem

  1. Jun 6, 2016 #1
    1. The problem statement, all variables and given/known data
    Find cscθ given sec θ = -2 sin θ >0

    2. Relevant equations
    I do not know where to begin or what equations to use.

    3. The attempt at a solution
    I am assuming there is a typo in the question and that there should be a comma sec θ = -2, sin θ >0.

    If so I got csc θ = 2√3 / 3
     
  2. jcsd
  3. Jun 6, 2016 #2

    SteamKing

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    Why not? How is the secant defined? The cosecant? Those would be good places to start.
     
  4. Jun 6, 2016 #3
    I am assuming there is a typo in the question and that there should be a comma sec θ = -2, sin θ >0.

    If so I got csc θ = 2√3 / 3
     
  5. Jun 6, 2016 #4

    SteamKing

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    Looks good.
     
  6. Jun 6, 2016 #5

    Ray Vickson

    User Avatar
    Science Advisor
    Homework Helper

    The question as written (no comma) also makes perfectly good sense; it says that ##0 < \sec \theta = - 2 \sin \theta##, and you need to use the definition of ##\sec## to get a solvable equation. You can get ##\sin \theta## and ##\cos \theta##, then compute ##\csc \theta##, which does NOT equal ##2 \sqrt{3}/3 = 2/\sqrt{3}##.
     
    Last edited: Jun 7, 2016
  7. Jun 7, 2016 #6

    SammyS

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    As Ray points out, the problem as stated makes sense and can be solved. If you are currently studying trig equations in your course, then that's probably not a typo. On the other hand, if you are studying the basics of trigonometric functions early in your course, then it very well may be a typo, similar to what you have concluded.

    The statement, ##\ \sec θ = -2 \sin θ >0 \,,\ ## is really two (or three) statements rolled into one.
    • ##\ \sec θ >0 \ ##
    • ##\ -2 \sin θ >0 \,,\ ## so that ##\ \sin θ <0 \ ##
    • ##\ \sec θ = -2 \sin θ ##
    The first two tell you what quadrant θ is in.
     
  8. Jun 7, 2016 #7

    Dr Transport

    User Avatar
    Science Advisor
    Gold Member

    recast [itex] sec(\theta) [/itex] as [itex] 1/cos(\theta) [/itex] and the solution falls out in about 2 lines...
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Trig problem
  1. Trig problem (Replies: 4)

  2. Trig problem (Replies: 1)

  3. Trig Problem (Replies: 1)

  4. Trig problem (Replies: 14)

  5. Trig problems (Replies: 7)

Loading...