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Thread: Basic "TRIGONOMETRY" Question

  1. #1

    Default Basic "TRIGONOMETRY" Question

    What is the formula for calculating the long line (Diagonal) if one corner is 90 degrees...??? If the length (Height & Width) of two lines meeting at 90 degrees are both known.......what is the formula for calculating the third line.......???

    Yes.......laying out footers.

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    Member logman 49's Avatar
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    4-5-6 method?

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    Member akriverunner's Avatar
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    A squared plus B squared = C squared


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    So if I take a "KNOWN" less5, less6............????

    Quote Originally Posted by logman 49 View Post
    4-5-6 method?

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    Member akriverunner's Avatar
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    Are you looking to find the long side of a triangle and you know the other two lengths?


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    NO.......If the footing is to be "X" long (a Known) and "Y" wide (also a known) and if all corners are to be "Right-angle" (90*) how does one calculate the corner to corner length.

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    Member akriverunner's Avatar
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    Default Basic "TRIGONOMETRY" Question

    The 3, 4, 5 method is used for checking square. Are you trying to square footings for a rectangle or square? Take each side you know and multiply by itself, add the two numbers together and find the square root of them. Answer will be the diagonal length


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    Last edited by akriverunner; 06-06-2014 at 12:23. Reason: add

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    Quote Originally Posted by AGL4now View Post
    NO.......If the footing is to be "X" long (a Known) and "Y" wide (also a known) and if all corners are to be "Right-angle" (90*) how does one calculate the corner to corner length.
    This is a right angle triangle. From your description, you are trying to find the long side (hypotenuse) of the triangle when you know the two shorter sides (X and Y). Essentially, you know the two measurements for the sides of the "L" and are trying to find the measurement that connects the two ends?

    If so, the equation given above is correct. The square of one length + the square of the next length = the square of what you are looking for. So, (X x X) + (Y x Y) = (C x C). You are looking for C, so once you get the first part of the equation solved, just get the square root and you have your answer.

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  10. #10

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    So.....34 feet wide squared is 1,156

    28 feet deep squared is 784

    when added together equals 1930

    Next question: what number when squared equals 1930......??? I miss my slide ruler.

    Thanks for the help.

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    43.93176527297759 roughly.

  12. #12

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    Based on the link above, 44.05

    Oh, it's 1940, not 1930

  13. #13

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    Quote Originally Posted by AGL4now View Post
    So.....34 feet wide squared is 1,156

    28 feet deep squared is 784

    when added together equals 1930

    Next question: what number when squared equals 1930......??? I miss my slide ruler.

    Thanks for the help.
    If you are using a computer to post here, you most likely have a calculator program built in. For windows computers, it is under the start-more programs-accessories-calculator. Just enter the number you are wondering about such as "1930" and then click on the square root button (the one that looks a lot like a check mark).

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    Member Frostbitten's Avatar
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    Quote Originally Posted by AGL4now View Post
    So.....34 feet wide squared is 1,156

    28 feet deep squared is 784

    when added together equals 1930

    Next question: what number when squared equals 1930......??? I miss my slide ruler.

    Thanks for the help.
    As colonel pointed out, 1156 + 784 = 1940....not 1930.

  15. #15

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    OK........So what number squared equals 1940.....???? Please


    Quote Originally Posted by Frostbitten View Post
    As colonel pointed out, 1156 + 784 = 1940....not 1930.

  16. #16

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    Quote Originally Posted by AGL4now View Post
    OK........So what number squared equals 1940.....???? Please
    The square root of 1940 is 44.0454 feet

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    Quote Originally Posted by colonel00 View Post
    Based on the link above, 44.05

    Oh, it's 1940, not 1930
    what he said

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    Thank You to everyone. I really appreciate the help.

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    AGL there is more to squaring a footing the just diagonals. Use batter boards. Run two parallel lines at your known width. Square the next line using 3 4 5 method or multible a of like 6 8 10. Then pull numbers to set the last line. Then only then check diagonals against each other
    That's pretty much how I do it most of the time. But here is a step by step for ya. Skip the trig!

    http://www.quikrete.com/PDFs/Project...AndFooters.pdf

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    Member 4merguide's Avatar
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    Quote Originally Posted by Bear View Post
    AGL there is more to squaring a footing the just diagonals. Use batter boards. Run two parallel lines at your known width. Square the next line using 3 4 5 method or multible a of like 6 8 10. Then pull numbers to set the last line.
    Exactly.....lay the batter boards out and do it right there on the ground to make sure it's right....3,4,=5 across....6,8,=10......12,16,=20 etc...

    Besides....trig makes my head hurt.

    Oh and btw....4,5,6 doesn't work.....
    Sheep hunting...... the pain goes away, but the stupidity remains...!!!

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