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    Re: cosine/haversine method
    From: Chuck Taylor
    Date: 2001 Feb 10, 10:48 PM

    Russell Sher wrote:
    > Does anyone have much experience using the cosine/haversine method of sight
    > reduction? As I understand it, this will calculate Hc, after which the
    > azimuth has to found using tables or formula. I am interested in finding
    > some suggestions on what is perhaps the easiest way to find Zn (or Z)...
    > (ABC tables, formula etc...)
    The traditional way, per the 1943 Bowditch, was to use the formula
            sin Z = sin t * cos d * sec h
    which was worked out with tables of the logarithms of the various
    trigonometric functions.  With a modern calculator, this would be
    equivalent to
            sin Z = (sin t * cos d) / (cos h)
    Chuck Taylor
    Everett, WA, USA

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