RE: [MATHEDCC] Why radians?

Stefan Baratto (sbaratto@yctc.net)
Mon, 1 Nov 1999 12:59:54 -0500

The real question is "why degrees?" Degrees are a mistake. Initially, the
Babylonian and Egyptian civilizations believed that it took 360 days for the
Earth to revolve around the sun (one year), hence each degree was analagous
to one day. This is, of course, an error.

Radians are a natural unit of measure. The length of the arc subtended by a
central angle of one radian on a unit circle is one unit long. A full
rotation is 2*Pi radians (as an angle measure and as the length of the
circumference of a unit circle).

Hope this helps.

Stefan Baratto

> -----Original Message-----
> From: Martin Kalmar [SMTP:MKalmar@fcc.cc.md.us]
> Sent: Monday, November 01, 1999 12:22 PM
> To: Mathedcc@archives.math.utk.edu
> Subject: [MATHEDCC] Why radians?
>
> When students ask (not often enough) why do we need to measure angles in
> radians, I know of no other answer than it makes things very convenient in
> calculus. This is fine for my calculus students who can see what the
> derivatives of trig functions would look like without radians, but what
> other answer can I give my pre-calculus students?
>
> Does anyone know of other good reasons for using radians?
>
> Does anyone know the history of radian measure? Who first used it and why?
>
> Martin Kalmar
> Frederick Community College
> Frederick, Md.
> mkalmar@fcc.cc.md.us
>
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