A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Lars Bergman
Date: 2020 May 9, 14:35 -0700
Dave, seems to be identical to my solution. When using Excel you do not need to calculate 180° minus azimuth; the reason I did it was that most log trig tables (including my Burton's Nautical Tables) only cover the range 0° to 90°. Then you need to consider how to find the log value for an angle larger than 90°. In this case we need log sin and log cos of an angle around 120°. Now sin 120°=sin(180°-120°) and cos 120°=-cos(180°-120°). An "n" behind the log in my sheet indicates that the value is negative. When summing the logs, if you have an odd number of "n"s the result is negative.