Trigonometry was, as a part of mathematics, until the renaissance almost exclusively usedin astronomy, and not as a mathematical theory. Plane ttrigonometry was used just as much as needed for spheerical trigonometry. There are many uses of trigonometric functions today. One of theese uses is visible in marine, specially in navigation. Numerical calculation of the shortest way between starting position and destination position, ie. great circle, and aproximation methods are the backbone of this paper. Paper does, at least partially, show us huge role of trigonometric functions in great circle sailing, and in marine in general
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