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Thread: Simple problem with triangle

  1. #1
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    Simple problem with triangle

    It's been many years since my geometry classes, but hoping someone will help me with this simple problem:


    Say you have a triangle where side a is 76mm, and side b is .5mm. What is side b if side A were to be 700mm?


    Is this a simple rule of 3 problem?

    Thanks!
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  2. #2
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    Re: Simple problem with triangle

    Quote Originally Posted by Kabibble View Post
    with this simple problem: Say you have a triangle where side a is 76mm, and side b is .5mm. What is side b if side A were to be 700mm? Is this a simple rule of 3 problem?
    Perhaps you should tell us what the rule of three is?

    As stated that are many possible answers.
    Does \angle A remain fixed? OR is this a similarity(proportionality) question?

    In other words we need more details.
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  3. #3
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    Re: Simple problem with triangle

    The rule of three is basically a:b = c:d where if you know three of those numbers you can extrapolate the 4th.

    In my situation the angle does not change.
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  4. #4
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    Re: Simple problem with triangle

    Then, WHY use a triangle?

    a/b = c/k
    a,b,c = givens; solve for k.

    Btw, google "rule of three".
    Your definition is from where?
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  5. #5
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    Re: Simple problem with triangle

    Interesting! I did google "rule of three" and got a page on the "rule of three writing". But there is also a page titled "rule or three math" which gives the definition kabibble gives. Admittedly, that is a Charles Dodgson (writing as "Louis Carrol"), in a book of (mostly mathematics) puzzles, refers to the "rule of three" repeatedly.
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  6. #6
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    Re: Simple problem with triangle

    By the way, Rule of three is also discussed here:

    https://en.wikipedia.org/wiki/Cross-...#Rule_of_Three
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    Re: Simple problem with triangle

    Quote Originally Posted by HallsofIvy View Post
    Interesting! I did google "rule of three" and got a page on the "rule of three writing". But there is also a page titled "rule or three math" which gives the definition kabibble gives. Admittedly, that is a Charles Dodgson (writing as "Louis Carrol"), in a book of (mostly mathematics) puzzles, refers to the "rule of three" repeatedly.
    The Reverend Mr. Dodgson probably taught this as university mathematics in 1860.
    Here is a reasonable reference.
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