Wrong question about parallel sides

Discussion in 'Geometry and Trigonometry' started by MathsforMaths, Feb 22, 2024.

  1. MathsforMaths

    MathsforMaths

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    This question appeared in my exam. Look at the figure and join db. Look at the second part of question. It is wrong.
     

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    MathsforMaths, Feb 22, 2024
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  2. MathsforMaths

    conway

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    Im just a philosopher, and a terrible mathematician. So we will have to wait for the pros....but it appears correct to me. (ab) is parallel to (cd). Perhaps I am missing something. Feel free to expand your point. "Proving" that they are is something else....I love when we find mistakes in our mathematics...tickles me to no end. I hope that you are right!
     
    conway, Feb 22, 2024
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  3. MathsforMaths

    Phrzby Phil

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    I agree. Tilt angles BAC and DCA inward identically. Initial conditions still hold.
     
    Phrzby Phil, Feb 22, 2024
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  4. MathsforMaths

    conway

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    Phrzby

    Can you expand on this? It would be appreciated!
     
    conway, Feb 22, 2024
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  5. MathsforMaths

    Phrzby Phil

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    Nothing to expand on. Draw the diagram as I said, keeping the initial conditions the same. Since the two sides are now tilted toward each other, they are not parallel.
     
    Phrzby Phil, Feb 22, 2024
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  6. MathsforMaths

    Phrzby Phil

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    By saying "Tilt angles BAC and DCA inward identically," I thought it would be obvious that one could do so by drawing it that way.

    But one need not actually draw it - the diagram with identically tilted sides exists whether drawn or not - visualized for example.

    It was a "mistake" because it cannot be proved because counter-examples exist - per my suggestion.
     
    Last edited: Feb 22, 2024
    Phrzby Phil, Feb 22, 2024
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    conway likes this.
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