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Homework Help: Trig question?

  1. Aug 15, 2008 #1
    Ok my math is a little rusty. I ran across a problem that states:
    "A park is being considered in a space between a small river and a highway as a rest stop for travelers. Boundary BC is perpendicular to the highway and boundary AD makes an angle of 75 Deg. with the highway. BC= 160.0 m , AD= 270.0 m, and the boundary along the highway = 190.0m long. What are the length of side AB and the magnitude of angle ABC?"

    I have attached a file that is almost identical to the one in the book. I need help figuring out where to start this problem(not an answer please). Any help would be appreciated.


    Attached Files:

  2. jcsd
  3. Aug 15, 2008 #2


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    Welcome to PF!

    Hi ur5pointos2sl ! Welcome to PF! :smile:

    I can't see your picture file yet, but I think the best way is probably to use x and y coordinates, starting with C as the origin. :wink:
  4. Aug 15, 2008 #3
    My problem is that I cant seem to use law of sine/cosine because there is always 2 things to be solved for. I think I am missing something.

    I put C at the origin and looked at it that way. If i seperate the figure into two triangles that doesn't seem to lead me anywhere either. I can solve for one but then the other I am completely stuck on.
  5. Aug 15, 2008 #4


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    You don't need coordinates. DO split the quadrilateral into two triangles. Solve the right triangle first. Find length of BD and the two angles. Then you have side-angle-side on the remaining triangle. Solve it.
  6. Aug 16, 2008 #5
    Thank you. That is exactly what I did last night except I solved for the right triangle then used law of cosine to solve for the other. I finally realized my answer was off because I was rounding to one decimal place.
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