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Subject: Re: Spherical Law of Cosines
From: Dan Allen (danallen46@XXX.XXX)
Date: Fri Oct 18 2002 - 17:44:49 EDT
Thanks to Bill Arden who pointed out yet another mistake of mine...
I have been writing these things while being very involved in other
matters and my memory has not been what it used to be...
sin(c) = sin(a)*sin(b) + cos(a)*cos(b)*cos(ab)
is what I should have written as the alternative version.
With apologies,
Dan
Begin forwarded message:
> From: ARDENW714@XXX.XXX
> Date: Fri Oct 18, 2002 12:22:00 PM US/Pacific
> To: danallen46@XXX.XXX
> Subject: law of cosines
>
> Hi, Dan -
>
> You wrote recently ...
>
> "Note too that there are equivalent ways of writing the spherical law
> of cosines. One can write it as
>
> cos(c) = sin(a)*sin(b) + cos(a)*cos(b)*cos(ab)
>
> where the pairs of sin/cos of a/b are switched."
>
> Isn't the left side of that equation SIN(c)? Or is that another
> substitution that I didn't know enough to make?
>
> I hope I haven't been doing that wrong - I've been using
> sin(Hc) = sin(lat)*sin(dec) + cos(lat)*cos(dec)*cos(LHA) and it seems
> to work correctly.
>
> Regards,
> Bill Arden
>
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