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Stuck on example

Discussion in 'Electronics Homework Help' started by pump, Oct 12, 2012.

  1. pump

    pump

    24
    0
    Nov 4, 2011
    Hi,
    My lecture has given the following but I don't see where he has got 8.1 from....
    Could some explain please?
    Example.JPG
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,174
    2,689
    Jan 21, 2010
    Put those numbers in your calculator, execute the cosh^-1 function on them, and divide the result.

    I get 8.0985163768965816846821597817253

    Surely the question isn't this simple?
     
  3. pump

    pump

    24
    0
    Nov 4, 2011
    Hi Steve,
    Thank you for your reply. I can also enter the last equation into a calculator and get that result. However I couldn't see where he has got 57.05 from? Please see attached screenshot.

    Thank you for taking the time to help me out here :)
     

    Attached Files:

  4. pump

    pump

    24
    0
    Nov 4, 2011
    Just looking again

    I can only get the same answer as him if I subtract 512.8 in the top half of the equation?
     
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,174
    2,689
    Jan 21, 2010
    You've missed a 1 and a closing parenthesis in your notes. you have "- )" where you should have written down "-1 )" then the closing parenthesis for the arccosh is missing.

    Can you see where?

    then substitute the numbers into it and the right answer comes out.

    You realise what that 1/2 at the end is, right?
     
  6. pump

    pump

    24
    0
    Nov 4, 2011
    The screenshots I have posted are from the lecturers notes which is why I am struggling to work the equation out. Just taking the top of the equation I get:

    cosh-1 (2.863 x 397.107 x 0.5)
    = cosh-1 (568.4586)

    Where the lecture has got :
    cosh-1 (57.05)

    No I don't understand why the 1/2 is there either :(
     
  7. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,174
    2,689
    Jan 21, 2010
    The 1/2 is raising the value inside the brackets to the 1/2th power (square root)
     
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