Why 360 degrees?

[Robust]

I wonder if there are others who, like myself, question why the circle is described by a circumference of 360 equally spaced angular degrees. Why not 240, 390 or some such?

[Moonchild]

I believe it may have something to do with a form of units called 'radians.'

Basically, 360 degrees = 2pi radians.

[Aki]

maybe this site will help:

http://id.mind.net/~zona/mmts/trigonometryRealms/degMinSec/degMinSec.htm

[Freethinker]

One clue as to why 360 is used has to do with the smaller scales it is broken into. Degrees are broken down further into minutes and seconds. Thus showing that "time" was the basis for "angles". But why 360?

 

The Chaldean dynasty in Babylon during the reign of Nebuchadnezzar (605-562 BC) had calculated (incorrectly we now know) that the year was 360 days long. They found this worked well for dividing things down. 60 can be divided evenly by 2, 3, 4, 5, 6 and 10. And 360 also by 8 and 9.

 

Thus it was an easy number to work with and had a basis connected to something physical, our year.

[Bo]

360 is just a convention; the unit is called `then a degree.

some people do use 100 gradians, or 2pi radians.

 

the difference is just like the difference between inches and centimeters or so; just a definition.

 

360 is a nice number, because there are many numbers by which you can devide 360 and get an integer number. (just like the 60 minutes in an hour)

 

Bo

[Robust]

Thanks, Moonchild, I think you may be right, for the radian is the same distance on the arc as the radius which subtends it. Puts things in proper perspective and one might carry on from there. What I'm after here is in trying to determine how the ancients who gave us the 360-degree circle arrived at that same conclusion.

[Robust]

Thanks for the site, Aki....I'll check it out.

 

 

"All things number and harmony." - Pythagoras

[Robust]

Freethinker, the 360-degree circle was established at least some 5,000 years before the Chaldean empire. Though I tend to agree it was that dynasty which led us astray. It seems that Pythagoras may have thought so also.

 

 

"All things number and harmony." - Pythagoras

[Robust]

Hi, Bo! I think 360 is much more than a convention....rather that it derives from highly sophisticated astronomical observation.

[Bo]

well i once heard a story that the 360 and the more or less 360 days in a year have somewhat the same origin, but i wouldn't know the details.

 

Bo

[Freethinker]

Originally posted by: Robust

Freethinker, the 360-degree circle was established at least some 5,000 years before the Chaldean empire.

Your saying you can show us specific math using 360-degrees in a circle almost 10,000 years ago?

 

I'd love to see references for this.

[Robust]

As I recall, Freethinker, the Chaldean empire did not come into existence until about 500 BC. The earliest pi value we have (which I believe is the correct one) dates some 5,000 years prior, so the 360-degree circle, Base 10 number system, etc. dates to that period and perhaps much earlier.

[Robust]

Moonchild, Hello! Ive been following up your suggestion regarding the radian and came up with yet another relevant formula: radius/radian = degree distance; the generally recognized one being circumference/360. I think you put me on the right track....and I thank you for that.

[Moonchild]

Uh....you're welcome.

 

My Pre-calc class is about to go into trigonometry in about two weeks...I'm very excited abot that, and if this string continues through that time I'll post anything else I learn in trig.

[Robust]

Good luck with the pre-calc, Moonchild....and keep me in mind. I get the greatest help from those who are still learning.

 

 

"All things number and harmony." - Pythagoras

[Moonchild]

Yeah, thanks.

 

Remember, genius w/o experience is like silver in the mine.

[Moonchild]

Also, remember this:

 

In a sine wave, 360 degrees is like a full wave, which is 2pi. (4 units total on x-axis).