A Spherical Triangle Computer for Marine and Air Navigation

Abstract

A simple analog computer, which solves the oblique and the right spherical triangle equation, is described based on the law of cosines. With three parameters of the oblique triangle as inputs, the fourth is computed with an accuracy better than ± 10 minutes of arc for most of the practical problems. The computer can be used to solve navigational problems such as the hour angle, course angle and great circle distance. Solutions for the right spherical triangle are obtained when one parameter is set to 90°.