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Help with distance between cities?

  1. Feb 26, 2012 #1
    1. The problem statement, all variables and given/known data
    Find the distance in kilometers between each pair of cities assuming they lie on the same north-south line:
    Panama City, Panama, 9° N and Pittsburgh, Pennsylvania 40° N

    2. Relevant equations
    All we talked about in class is that θ = S/r

    3. The attempt at a solution
    I'm really not sure what to do... I assume I'm supposed to be solving for s or r, given that θ1 is 9 and θ2 is 40 but...I'm still not sure what to do.
  2. jcsd
  3. Feb 26, 2012 #2


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    Homework Helper

    The distance between them is along an arc - if you assume the earth is a perfect sphere - we commonly do.
  4. Feb 26, 2012 #3
    So what am I supposed to do? All I'm given is 9 and 40. I know I need S or R, but I don't know how to get them.
  5. Feb 26, 2012 #4
    Nevermind, I think I've got it. Apparently the radius of Earth is 6400 km. So I converted the given θ's to radians and then solved for S for the both of them, then subtracted to get the distance between the two :D Thanks for the hint, PeterO
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