Abu al-Wafa' Buzjani

Born in June 940, Abu al-Wafa' Buzjani spent his career in Baghdad pushing past the limits of the geometry he inherited. He rewrote spherical trigonometry with new precision, mapping the six trigonometric lines of an arc and how they spoke to each other. His arithmetic textbook for merchants broke ground by using negative numbers—the first time they appeared in a medieval Islamic text. He compiled tables of sines and tangents at fifteen-minute intervals, tools that would guide astronomers for centuries. His Almagest became required reading across the medieval Arabic world long after his death…