The method of conformal mapping is a tool to achieve this solution. 保角映射法就是一种寻求这个解的工具。
The Geocentric angle should be avoided as possible.Two samples were given to discuss the cases when the geocentric angle must be used, as well as the results and error analyses. 讨论了需要利用地心角映射关系进行计算时的两种情况，同时给出计算结果和误差分析。
