Radio and Airplane Distances

With the recent development of the radio and the airplane considerable interest has arisen in the problem of determining the shortest distance between any two points on the earth's surface. The writer proposrs in the following discus. ion to treat the problem in a manner mathematically exact, and at the same time make the explanation simple enough to be understood by any high school student who has had experience with elementary problems involving sines and cosines. It is hoped that teachers may find the discussion helpful in providing supplementary work for high school mathematics classes, and for reference reading on the part of interested students.