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Math Help - Find DC

  1. #1
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    Find DC

    To measure the distance (DC) across a pond, a surveyor takes points A and B so that AB is parallel to DC. If AB = 60 feet, EB = 48 feel, and ED = 80 feet, find DC.
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  2. #2
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    Quote Originally Posted by symmetry View Post
    To measure the distance (DC) across a pond, a surveyor takes points A and B so that AB is parallel to DC. If AB = 60 feet, EB = 48 feel, and ED = 80 feet, find DC.
    Where/what is E?

    RonL
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  3. #3
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    Hello, symmetry!

    To measure the distance DC across a pond,
    a surveyor takes points A and B so that AB \parallel DC.

    If AB = 60\text{ ft},\;EB = 48\text{ ft},\;ED = 80\text{ ft}, find DC.
    You forgot to tell us where point E is, but I have a good guess.
    Code:
        D * - - - - - - - - - - - - - - - * C
                *                       *
                   80 *               *
                            *       *
                                  *E
                                *       * 48
                              *               *
                          A * - - - - - - - - - - - * B
                                       60

    From the similar triangles, we have: . \frac{CD}{80} \:=\:\frac{60}{48}

    Therefore: . CD \:=\:100\text{ ft}

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  4. #4
    Eater of Worlds
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    In real-life, the person helping the surveyor would go to the other side of the pond with a prism and the surveyor would measure the distance with the transit. That's no fun, though. Too easy.
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  5. #5
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    ok

    Thank you all, especially soroban. Soroban did a great job with the picture and reply.

    Thanks!
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