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Math Help - Trig question I cant figure out

  1. #1
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    Trig question I cant figure out

    Jim wanted to swim from his dock across the lake to Julie's dock. He estimated the distance by first standing at a point 200m down the beach from his dock, and from this point he found his dock was N70*E and Julie's dock was N20*E. He then went back to his dock and found Julie's dock was N10*W of it. What is the distance between the docks?

    I have been on this problem for 2 hours, my Math teacher was kind enough to give us the final answer 306.4m , however he wants to see the work and I have no idea how he went there, I've tried diagramming it out and labeling the angles as well as using the Law of Sines and Law of Cosines formula's. The closest I got 297.5 . Any help would be appreciated.

    PS. the * is degrees.
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by Yash View Post
    Jim wanted to swim from his dock across the lake to Julie's dock. He estimated the distance by first standing at a point 200m down the beach from his dock, and from this point he found his dock was N70*E and Julie's dock was N20*E. He then went back to his dock and found Julie's dock was N10*W of it. What is the distance between the docks?

    I have been on this problem for 2 hours, my Math teacher was kind enough to give us the final answer 306.4m , however he wants to see the work and I have no idea how he went there, I've tried diagramming it out and labeling the angles as well as using the Law of Sines and Law of Cosines formula's. The closest I got 297.5 . Any help would be appreciated.

    PS. the * is degrees.
    Are you sure your diagram is correct? See the diagram below. that is what your diagram should look like. You want to find the length marked "x"

    i suppose you can understand everything else in the diagram. the "N" means "North"
    Attached Thumbnails Attached Thumbnails Trig question I cant figure out-docks.png  
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  3. #3
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    Ok, my graph was just a little bit off from that, thanks a ton ill try and do the rest myself now
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  4. #4
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    Ok, still having trouble here, I filled the rest of the supplementary angles in and then tried to use the Law of Sines

    a/Sin70 = 200/Sin30

    which then gives:

    Sin70(200)
    ___________
    Sin30

    =
    375.87 and I know thats wrong because the final answer should equal 306.4
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