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Homework Help: Phsyics problem. I must find distance in Kilometers.

  1. Aug 29, 2007 #1
    1. The problem statement, all variables and given/known data
    You are driving into St.Louis Missouri, and in the distance you see the famous Gateway-to-the-west arch. This monument rises to a height of 192 m. You estimate your line of sight with the top of the arch to be 2.0 degrees above the horizontal. Approximately how far (In Kilometers) are you from the base of the arch.

    Height= 192 m
    Angle= 2.0 degrees

    2. Relevant equations[/b
    Definition of Cos, Sin, and Tan or the inverse trigonometric functions

    I have no clue on what I should do.
    This is what I did.
    H adjacent= 192/tan(2.0)= 5498m and then I converted it to KM and I got 8848 km. This answer is way off, and I know I'm doing something wrong.
  2. jcsd
  3. Aug 29, 2007 #2
    You did the equation right.

    tanĂ˜ = y/x

    x = height/tan2

    x = 5498m

    How many meters are in a kilometer?
  4. Aug 29, 2007 #3


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    You were doing great until you tried to convert the units. What strange conversion formula are you using? m -> km just involves dividing by 1000.
  5. Aug 29, 2007 #4
    1,000 meters equal 1 kilometer, oh no wonder I had a reference sheet that said 1 KM equals .6214 Meters. Ok so the answer is 5.498. Thank you for helping me out.
    Last edited: Aug 29, 2007
  6. Aug 29, 2007 #5


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    km=0.6214 MILE. I wouldn't use the same abbreviation for meter and mile!
  7. Aug 29, 2007 #6
    Oh lol no wonder. In my conversion factor reference it just had m as the symbol, so it confused me.
  8. Aug 29, 2007 #7
    Remember, it is a KILOmeter. Kilo means 10^3, so 1000meter. ;)
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