360 degrees?

[Catso]

How did we end up with a circle being split in 360 degrees? Seems a very peculiar number.

[jake-the-peg]

Wikipedia reckons it comes from early approximations to the number of days in the year.

Not quite sure I buy this because early astronomers were surprisingly sharp and the Ancient Egyptians for instance would certainly have known it was 365 not 360 days.

But 360 is a pretty handy number. It has an awful lot of factors - 2,3,4,5,6,8,9,10.. oh I'm getting bored now you get the idea.

More recently scientists started to use radians in preference to degrees because it's relationship to a circle is not arbitary like degrees and so things work out nicely.

If you draw 2 radii from the centre of a circle to its edge so that the length of the piece of the circumference beween them is the same as the radius - that angle is a radian - it's about 57 degrees and 2xpi radians = 360 degrees

[CT]

I read somewhere it is realted to Sumerian(sp) or Mesoptamian maths. They used the number 60 frequently. 360 is 6 times this value. This seems a bit incomplete. I shaall return when I have more info.

[CT]

This site gives some more info. Basically, the Mesopotamians used a sexagesimal (base 60) numerical system. http://it.stlawu.edu/~dmelvill/mesomath/index. html

[CT]

Also just found this too http://mathforum.org/library/drmath/view/57578 .html

[heathfield]

The Babylonians number system used the base number of 60. (We use a base number of 10 nowadays in our decimal system). They were in difficulty doing maths when it came to division - they didn't really fancy handling those irksome remainders, and wanted to work in whole numbers. By allocating their base number of 60 to the angles of a triangle (a shape with the least number of sides), when it came to more complex shapes -square, pentagon, hexagon, etc, etc, each angle of the figure was represented by a whole number of degrees. Under their system, the sum of the angles in these shapes is 360 degrees, and each angle is a whole fraction of the total. This is kinda very useful! Of course, that left 7, 11, 13, etc, sided figures where division produced remainders of fractions, but that didn't bother them too much - they just got along without them, thank you.

Despite those remainders in division, they put up with them long enough to work out a fairly accurate value for π, though they are known to have used the approximation of 25 / 8. Note that this gives a less accurate figure for π than the approximation we use today of 22 / 7. But it did mean they were using their preferred divisor of 8.