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Thread: Calculate Chord w/o Known Angle at Circumference

  1. #1
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    Calculate Chord w/o Known Angle at Circumference

    ---------------------------
    What I'm trying to do
    ---------------------------
    Determine the end of my cut.
    Using a ruler easy takeoff .
    Can it be done mathmatically?

    ------------
    Problem
    ------------
    I have a 10 inch saw blade. The radius in naturally 5 inches.
    I want to measure down a distance (can be any but say 1/4 inch) from the circumference (top of the blade)
    to the table top. From this right angle intersection, I want to measure the distance to the blade (circumference)
    where it intersects the table top.
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  2. #2
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    Re: Calculate Chord w/o Known Angle at Circumference

    Calculate Chord w/o Known Angle at Circumference-saw.jpg
    I think this is what you are trying to do, where x is the measurement from the top of the blade to the tabletop.
    To find w you need to use Pythagoras' Rule.
    $\displaystyle w^2 + (5-x)^2 = 5^2$
    Can you rearrange that to get a formula for w?
    Thanks from topsquark
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  3. #3
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    Re: Calculate Chord w/o Known Angle at Circumference

    Debsta:

    Thanks for your efforts on my behalf.
    Now that I see what was done, makes sense.
    Re: In terms of w:

    w = sqrt(25 - ((5 - x) * (5 - x))

    or general formula of:

    w = sqrt((radius * radiius) - ((radius - x) * (radius - x))) where x is the distance from the top of the blade to the table.
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  4. #4
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    Re: Calculate Chord w/o Known Angle at Circumference

    Yes that's correct.
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