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    Re: The Great Circle Challenge
    From: Samuel L
    Date: 2014 Dec 27, 04:05 -0800

    Thanks, Gary. 'Gave it a try and it works.

    Sam L.

     

     

    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
       
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