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Math Help - Weird Question Different Answers?

  1. #1
    Member classicstrings's Avatar
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    Weird Question Different Answers?

    When I work out x I get 2 different answers. Wondering if someone can explain?
    Attached Thumbnails Attached Thumbnails Weird Question Different Answers?-untitled1.jpg   Weird Question Different Answers?-untitled.jpg  
    Last edited by classicstrings; August 3rd 2006 at 07:44 AM.
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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by classicstrings
    When I work out x I get 2 different answers. Wondering if someone can explain?



    These links don't work so noboby will know what the question/s is/are.

    RonL
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  3. #3
    Member classicstrings's Avatar
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    Quote Originally Posted by CaptainBlack
    These links don't work so noboby will know what the question/s is/are.

    RonL
    Done. Still dont know why two values of x come up. (it isnt possible!)
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  4. #4
    MHF Contributor Quick's Avatar
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    Quote Originally Posted by classicstrings
    Done. Still dont know why two values of x come up. (it isnt possible!)
    I don't think sine works unless they're right triangles
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  5. #5
    Grand Panjandrum
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    Quote Originally Posted by classicstrings
    When I work out x I get 2 different answers. Wondering if someone can explain?
    Briefly; there is no such triangle if the angle marked as 60 degrees is that,
    and the parallel lines are, and the lengths are as indicated, then your angle
    marked as 50 degrees will in fact be more like 40 degrees, ie the data you
    have been given is inconsistent, so of course you get different answers
    depending on how you calculate things.

    RonL
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  6. #6
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by Quick
    I don't think sine works unless they're right triangles
    For the record, both the Law of Sines and Law of Cosines work on any triangle.

    -Dan
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  7. #7
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    Hello, classicstrings!

    The diagram is quite impossible . . . They lied to us!
    Code:
                  C
                  *
                 *  *
                *     *
               *        *
          b=4 *           * a
             *              *
            *                 *
           * 60                *
          * * * * * * * * * * * * *
          A         c=6           B

    Law of Cosines: . a^2\:=\:b^2 + c^2 - 2bc\cos A

    We have: . a^2\:=\:4^2 + 6^2 - 2\cdot4\cdot6\cos60^o\:= \:28\quad\Rightarrow\quad a \,= \,\sqrt{28} \,= \,2\sqrt{7}


    Law of Sines: . \frac{\sin B}{b}\,=\,\frac{\sin A}{a}

    We have: . \frac{\sin B}{4}\,=\,\frac{\sin60^o}{2\sqrt{7}}\quad \Rightarrow\quad \sin B \:=\:\frac{4\sin60^o}{2\sqrt{7}}\:=\:0.654653671

    Therefore: . B\;=\;\sin^{-1}(0.654653671)\:=\: 40.839339654 \quad\Rightarrow\quad B \:\approx \:41^o


    See? . . . and they told us that B\,=\,50^o

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