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Re: Gnomonic Charts - Usable Zones
From: Robin Stuart
Date: 2018 Jan 19, 08:06 -0800
From: Robin Stuart
Date: 2018 Jan 19, 08:06 -0800
Bob,
In Bowditch 2002 you can find this under 2406. Great Circle Sailing by Computation.
The necessary formulas can be found by applying the cosine and sine rules to Figure 2406. Starting at a latitude, longitude L0, λ0 and traveling a distance D(°) on a course C° measured East from North the necessary formulas are:
sin L = sin L0 cos D + cos L0 sin D cos C
sin ( λ - λ0 ) = sin D sin C / cos L0
An alternative method can be found in section 3 here.
Regards,
Robin Stuart
