Applied mathematics in the tenth century: Abu'l-wafā' calculates the distance baghdad-mecca

SummariesIn a compact, two-page presentation, an Iranian scientist of the tenth century illustrates the determination of the great circle distance between two points on the earth's surface. His first method employs a technique, well known in his time, for calculating the direction of Muslim prayer. The second method, perhaps of Indian provenance, uses the tangent and versed sine functions. The computations are precise to about one part in a hundred thousand. A solution by an analemma is included