Thanks tgq, but
   rotate<(degrees(atan2(1,2))),0,0>
is not exactly the same as
  rotate<30,0,0>
 - it is a little off as I suspect it is using the arc of a radian circle
instead of straight lines


"Trevor G Quayle" <Tin### [at] hotmailcom> wrote in message
news:web.46703ec3f87630f4c150d4c10@news.povray.org...
> Marc Schimmler <mar### [at] webde> wrote:
> > TheMightyZog schrieb:
> > > I'm ashamed to have to ask this, but I just can not remember how to
> > > calculate an angle in degrees if I know the opposite and adjacent side
of a
> > > right-angled triangle.
> > >
> > > My only excuse is that I'm an OAP and school was just years ago and
then
> > > radians were not taught!
> > >
> > > Help!
> > >
> > > Thanks
> > > Zog
> > >
> > >
> >
> > If it looks like this
> >
> >         alpha
> >       /|
> >    h /=|
> >     /  | o
> >    /  .|
> >    -----
> >      a
> >
> > alpha = atan (a/o)
> > alpha = acot (o/a)
> > alpha = asin (a/h)
> >
> >
> > Is this what you wanted ... POVCODE?
> >
> > Marc
>
> Better to use atan2(a,o).  Handles situation where o is zero.
> Also note the results of these is in radians to convert to degrees use
> degrees(A) in POV (or A*180/pi by hand).
>
> -tgq
>
>
>

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