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Math Help - How far was the pilot from starting point?

  1. #1
    Newbie Adikz's Avatar
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    How far was the pilot from starting point?



    Please help me, I'm not really good with trigo..


    A pilot flew for 210 miles at 21degree and then 147 miles at 162 degree. How far was he from starting point?
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  2. #2
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    Re: How far was the pilot from starting point?

    start by making a sketch of the problem ... looks to me like a task involving the cosine law.
    Attached Thumbnails Attached Thumbnails How far was the pilot from starting point?-trigprob1.png  
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  3. #3
    Newbie Adikz's Avatar
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    Re: How far was the pilot from starting point?

    Thanks for the diagram sir..
    ∠ABC = 21 + (180 - 162) = 39 Is that correct sir?
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    Re: How far was the pilot from starting point?

    Quote Originally Posted by Adikz View Post
    Thanks for the diagram sir..
    ∠ABC = 21 + (180 - 162) = 39 Is that correct sir?
    if you mean the acute angle at the top of the position triangle, yes.
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  5. #5
    Newbie Adikz's Avatar
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    Re: How far was the pilot from starting point?

    Using the law of cosines:
    This will be my new formula right?

    b = √(210 + 147 - 2 * 210 * 147 * cos 39)
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  6. #6
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    Re: How far was the pilot from starting point?

    formula is a^2+b^2 - c^2 / 2ab = cos 39 deg Solve for c given a and b
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  7. #7
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    Re: How far was the pilot from starting point?

    Quote Originally Posted by Adikz View Post
    Using the law of cosines:
    This will be my new formula right?

    b = √(210 + 147 - 2 * 210 * 147 * cos 39)
    correct
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  8. #8
    Newbie Adikz's Avatar
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    Re: How far was the pilot from starting point?

    Thanks..
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