# [Python-ideas] Trigonometry in degrees

Steven D'Aprano steve at pearwood.info
Fri Jun 8 02:59:03 EDT 2018

```On Fri, Jun 08, 2018 at 03:55:34PM +1000, Chris Angelico wrote:
> On Fri, Jun 8, 2018 at 3:45 PM, Steven D'Aprano <steve at pearwood.info> wrote:
> > Although personally I prefer the look of d as a prefix:
> >
> > dsin, dcos, dtan
> >
> > That's more obviously pronounced "d(egrees) sin" etc rather than "sined"
> > "tanned" etc.
>
> Having it as a suffix does have one advantage. The math module would
> need a hyperbolic sine function which accepts an argument in; and
> then, like Charles Napier [1], Python would finally be able to say "I
> have sindh".

Ha ha, nice pun, but no, the hyperbolic trig functions never take
arguments in degrees. Or radians for that matter. They are "hyperbolic
angles", which some electrical engineering text books refer to as
"hyperbolic radians", but all the maths text books I've seen don't call
them anything other than a real number. (Or sometimes a complex number.)

But for what it's worth, there is a correspondence of a sort between the
hyperbolic angle and circular angles. The circular angle going between 0
to 45° corresponds to the hyperbolic angle going from 0 to infinity.

https://en.wikipedia.org/wiki/Hyperbolic_angle

https://en.wikipedia.org/wiki/Hyperbolic_function

> [1] Apocryphally, alas.

Don't ruin a good story with facts ;-)

--
Steve
```