1. operational research is an important professional basic course of modern management. It is a new discipline developed in the early 1930s. Its main purpose is to provide scientific basis for managers to make decisions. It is one of the important means to realize effective management, correct decision-making and modern management. Relatively speaking, it is very difficult to test people's logical thinking and statistical ability.

2. Navigation mathematics is an important basic course for ship driving major in navigation secondary school, and spherical triangle is one of the main contents of navigation mathematics. It is an important method to calculate the ship's position, sailing direction and distance. And it is difficult to master advanced mathematics and other disciplines.