degrees and radians.

[Simon Foster]

On Sun, 05 May 2002 00:25:55 GMT, Tim Hammerquist <tim at vegeta.ath.cx>
wrote:

>Simon Foster graced us by uttering:
>> "Tim Hammerquist" <tim at vegeta.ath.cx> wrote:
>> > > Radians are what trig is based on. Otherwise the formula for the
>> > > area of a circle would be 'A = 360r'; since when does a unit
>> > > circle have an area of 360 square units?
>> 
>> Where do you get this from?  A = pi * r^2?
>
>You're right. Not enough coffee and too much time passed since college
>trig. =) Correction:
>
>: If trig were based on degrees, the following would be true for a
>: unit circle:
>:
>:   [ A = (180 * r^2) = 180 sq. units ]
>:   [ C = (360 * r)   = 360 units     ]
>
>Thus:
>
>  "since when does a unit circle have an area of 180 sq. units?"
>                                                 ^^^^^^^^^^^^^
>


I think you need more coffee!  Surely PI is "3 and a bit"!  The
area of a unit circle is pi.  How big do you make it?


>> > > OTOH, `man 3 sin` on my system documents the sin() function of
>> > > the C math library _is_ documented as taking radians. On a POSIX
>> > > system, this is usually what is called by Ruby's Math.sin()
>> > > method.
>> 
>> Maybe he's not on Unix?
>
>My handy copy of the Turbo C++ 3.0 Library Reference manual from my
>MS-DOS version of the software also documents sin() as taking a value in
>radians. (C)1990.  A.D.  So this is far from new. One might say it's a
>standard...  A trig calculator's default setting doesn't dictate the
>default of the world at large.
>
>Furthermore, not all *nix systems are POSIX-compliant. And very few
>POSIX-compliant systems are _completely_ compliant with the POSIX
>standard.
>
>My only intent in mentioning POSIX was that on most *nix systems (esp.
>POSIX ones), you can #include<math.h> and compile and expect to call
>a sin() function (that, btw, takes its argument in radians). Other
>PC-oriented operating systems lack a standard math lib "out-of-the-box".
>
>Tim Hammerquist

You're right here, I've never seen a trig call that didn't
expect the argument in rads.

--
Simon Foster
Somewhere in the West of England