The study of
geodesics on an ellipsoid arose in connection with geodesy specifically with the solution of
triangulation networks. The
figure of the Earth is well approximated by an
oblate ellipsoid, a slightly flattened sphere. A
geodesic is the shortest path between two points on a curved surface, i.e., the analogue of a
straight line on a plane surface. The solution of a triangulation network on an ellipsoid is therefore a set of exercises in spheroidal trigonometry .