1436-1476

German mathematician and astronomer who introduced Arabic algebraic and trigonometric methods to Europe, thus providing a systematic basis for their further development. In De triangulis omnimodis (1533) he developed the earliest statement of the cosine law for spherical triangles, and Tabulae directionum (1475) contains a valuable table of tangents. Regiomontanus also played a key role in reforming astronomical studies in fifteenth-century Europe by emphasizing and acting on the need for new and improved observations.