> >
> > If you are using the calculator within Windows, for example, you
> will see a
> > button for COS and also another for INV. If you want the arccos, ie. the
> inverse of
> > the cosine, enter your value, hit the INV box to check it off and then hit
> COS.
> >
> Mathematically, arccos returns a value in radians = 180 degrees / PI() =
> 57.29578
> The formula given assumes it is returned in degrees, which is the default in
> Windows' Calc, but not in Excel and other programming systems - be careful
> about that (also you should select menu View / Scientific to SEE the
> functions - in Standard cos and arccos can be used by TYPING o and io)
Bjoern,
Thanks for pointing out that the calculator must be in "View/Scientific" mode as
I forgot to mention that bit of trivia. I always have it in that mode and it is
something that I inadvertently took for granted.
> Anthony also asked 'at what altitude is the object '- this formula is for 0
> degrees, on (see-level) horizon.
I am not the one who asked but the reply and content are what really matter ....
:-)
Anthony.
> To find the ground range for another value, use the same formula for another
> Earth radius, then subtract the distance corresponding to the elevation you
> want (a).
> With R=6371 km and a in degrees:
>
> DIST = R * {arccos[cos(a)*R/(R+HEIGHT)] / 57.29578} - a * R / 57.29578
>
> assuming your calculator works completely in degrees. If using radians, use
> DIST = R * arccos[cos(a / 57.29578)*R/(R+HEIGHT)] - a * R / 57.29578
>
> With HEIGHT = 200 km, this gives for
> a=0 DIST=1576
> a=5 DIST =1113
> a=10 DIST = 810 ...
> a=85 DIST = 17
>
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