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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: query
From: Dan Allen
Date: 2002 Aug 21, 10:58 -0700
From: Dan Allen
Date: 2002 Aug 21, 10:58 -0700
On Wednesday, August 21, 2002, at 10:34 AM, Mitch B Burrill wrote:
> If I am at lat1, long1, and go XXX nm at TC YYY,
> What is the exact formula from spherical trigonometry to get lat2,
> long2 ?
> I have looked everywhere for this, I must be doing something wrong.
Check out http://williams.best.vwh.net/avform.htm
which has this:
Lat/lon given radial and distance
A point {lat,lon} is a distance d out on the tc radial from point 1 if:
lat=asin(sin(lat1)*cos(d)+cos(lat1)*sin(d)*cos(tc))
IF (cos(lat)=0)
lon=lon1 // endpoint a pole
ELSE
lon=mod(lon1-asin(sin(tc)*sin(d)/cos(lat))+pi,2*pi)-pi
ENDIF
This algorithm is limited to distances such that dlon
