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    Re: The Great Circle Challenge
    From: Gary LaPook
    Date: 2014 Dec 26, 17:59 -0800
    A slightly shorter formula is to take the arc cosine instead of arc sine, then you do not have to do the subtraction from 90. The rest of the formula remains unchanged.

    Your formula:

    90-sin-1((sin(21d 57min) x sin(-41.5d) + cos(21d 57min) x cos(-41.5d) x cos(334d 10min))
    Multiply the answer by 60

    Slightly better formula:

    cos-1((sin(21d 57min) x sin(-41.5d) + cos(21d 57min) x cos(-41.5d) x cos(334d 10min))
    Multiply the answer by 60


    From: Samuel L <NoReply_SamuelL@fer3.com>
    To: garylapook---.net
    Sent: Friday, December 26, 2014 1:11 PM
    Subject: [NavList] Re: The Great Circle Challenge

    'Hope this is right;
     
    Distance= 4,069 nm
    Method-
    90-sin-1((sin(21d 57min) x sin(-41.5d) + cos(21d 57min) x cos(-41.5d) x cos(334d 10min))
    Multiply the answer by 60
     
    Initial Bearing- 154d
    Method-
    180 + tan-1(sin(334d 10min) / (cos(334d 10min) x sin(41.5d) - cos(41.5d) x tan(-21d 57min))
     
    Sam L.


       
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