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Math Help - Help with formula please

  1. #1
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    Help with formula please

    Hi there,

    Wondering if someone could help me out with formula to calculate 2 sides length of a 5 sided shape?

    For the attached image I have the following dimensions:

    A, B and C are all 700 mm

    I need to calculate D and E where D = E

    Would really appreciate it if someone could either provide a formula or explain how to structure the formula.

    thanking you in advance.

    Mark
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  2. #2
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    Re: Help with formula please

    The side of a square with diagonal d (here d = 700) is \frac{d\sqrt{2}}{2}.
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  3. #3
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    Re: Help with formula please

    Hi infoweb,
    If you mean that A+B+C = 700mm there is no unique solution.There is no formula but you can calculate d by assuming A =a fraction of A and C another fraction of d.Express the total of the three sides in terms of d.Equate to 700mm
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  4. #4
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    Re: Help with formula please

    Hi there,

    Thanks for the quick responses. It's been over 20 years since I've done any math like this so I'm totally out of touch!

    @Bjhopper

    Sorry, I didn't make my self clear enough:

    A= 700
    B= 700
    C= 700

    I now need to work out the length of E and D which should be equal to each other.

    I tried the formula that emakarov provided but the answer I got didn't seem correct (494.97) not sure if that relates to the length of E and D as it seems too short.

    Mark.
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  5. #5
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    Re: Help with formula please

    Quote Originally Posted by infoweb View Post
    I tried the formula that emakarov provided but the answer I got didn't seem correct (494.97) not sure if that relates to the length of E and D as it seems too short.
    B\sqrt{2}/2 gives you the side of the square whose diagonal is B. Thus, D=A+B\sqrt{2}/2.

    Edit: This ignores the thickness of the segments.
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