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Why there are 360 degress in a circle

  1. Jan 19, 2012 #1
    Mentor comment: Harmony360 original post violated our rules. The new wording is mine. D H

    So, why there are 360 degress in a circle?
    Last edited by a moderator: Jan 20, 2012
  2. jcsd
  3. Jan 19, 2012 #2


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    It was arbitrarily chosen.

    Well, of course, there was historic reasons as to why it was done, but there is no fundamental reason to use 360 degrees.
  4. Jan 19, 2012 #3
    There are 360 degrees in a circle for historical reasons. It's entirely arbitrary. You could use any number at all. You could say there are 2pi radians in a circle and everything would work out the same. Perhaps 360 was chosen because it's more or less the number of days in the year, and 360 has a lot of divisors.

    I didn't follow the details of your chart, but it looks like some kind of cranky mysticism. There is no fundamental reason for dividing a circle into 360 parts, any more than there's anything meaningful about there being 12 inches in a foot.
    Last edited: Jan 19, 2012
  5. Jan 19, 2012 #4
    Doesn't it have something to do with Base 60? Much like themetric system is based on decimals?
  6. Jan 19, 2012 #5


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    Hey Harmony360 and welcome to the forums.

    You might get hints by studying the Babylonians. They used a base 60 number system by default and this might be a connection to the use of 360 degrees for use with time.

    They certainly used it for time (this is where we get minutes and seconds from), so its possible that they used it in an extended way for geometry as well.
  7. Jan 19, 2012 #6


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    yes, blame the babylonians (i always do).

    for a time, it was thought that the year had 360 days in it, which would make 12 months of 30 days each. note that 12 is 1/5 of 60, and 30 is 1/2 of 60, so these are "convenient" fractions in a base-60 number system.

    alas, it took astronomers some time to realize that this estimation of a solar year was incorrect. we have been paying for it with various calendrical "corrections" ever since (with bizarre conventions of leap years, and mis-matched month lengths, not to mention the whole gregorian/julian snafu).

    apparently, early philosophy literally thought that life was circles within circles, with everything lining up like some grand cosmic clock. the gods themselves created this order, and although such a notion may seem on the surface ludicrous, it persists in many of the common elements of language and thought (including, ironically, a great deal of relatively "modern" science).

    early astronomers also thought that the lunar cycle and the solar cycle were synchronized (a quaint reminder of this is still evident on many old clock dials, and even some wrist-watches), which is how subdivisions of solar years came to be called "moons" (months).

    which goes to show that an idea, even if totally wrong, may well outlive its usefulness, causing hair-pulling for young geometry students everywhere.
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