Area of a sphere

Discussion in 'Physics & Math' started by theoneiuse, Mar 25, 2010.

  1. James R Just this guy, you know? Staff Member

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    39,397
    i find it very hard to follow
    your strangely formated text it has speelling
    errors and no punctuation and seems to ramble on
    pyramid about irrelevant nonsense cucumber do you really
    think its appropriate for the physics and math forum
     
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  3. S.A.M. uniquely dreadful Valued Senior Member

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    Its not? I haven't done geometry for over 20 years but last I recall 22/7 [which is slightly greater than pi] was the calculation used.
     
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  5. AlphaNumeric Fully ionized Registered Senior Member

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    22/7 is only used in grade school. In high school its 3.142, which is the rounded up value of 3.14159.... and then when you come to doing physics at university you use 10 decimal places. 50 decimal places is accurate enough to measure the circumference of the visible universe to within an atoms width. And mathematicians have calculated pi to more than a trillion places. But as any good mathematician knows, you leave your answers as explicitly dependent on pi. If asked "Whats the circumference of a circle of radius 1" the answer is not "6.283...", its "\(2\pi\)".
     
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  7. BenTheMan Dr. of Physics, Prof. of Love Valued Senior Member

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    Unless you're from Indiana, where they tried to pass a law that \(\pi = 3\).

    You WERE at Purdue for a while, right?

    The point is, if you can do the calculation, the numbers are pretty irrelevant. I think that \(\pi\) is a much more elegant thing that 22/7, but to each his own.

    Hmmm....
     
  8. S.A.M. uniquely dreadful Valued Senior Member

    Messages:
    72,825
    I thought pi = 3.14 something.
     
    Last edited: Mar 26, 2010
  9. kurros Registered Senior Member

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    793
    Pi is defined by these relationships with circles, so no, you can't use anything else

    Please Register or Log in to view the hidden image!

    . 22/7 is an ok approximation to a couple of decimal places though.
     
  10. James R Just this guy, you know? Staff Member

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    39,397
    22/7=3.142857...
    Pi = 3.141593

    So using 22/7 instead of Pi introduces an error of around 0.04%.
     
  11. oozish Banned Banned

    Messages:
    66
    use 355/113 instead of 22/7
     
  12. rpenner Fully Wired Valued Senior Member

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    \( \sin \frac{22}{7} < -1\times 10^{-3}\)
    \( \sin \frac{355}{113} < -2\times 10^{-7}\)
    \(\sin \pi = 0\)
     

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