MATH
Al-Khwarizmi wrote 2 very important books. In one he explained how to use the Indian concept of the 10 digit number system and in the other he explained algebra. From Greece came geometry and trigonometry. Muslim scholars combined the 3 ideas and applied more Algebra into the solution of geometric problems. Which allowed them to refine Trig to use the simpler functions of sin, cos, and tan. This combined with the astronomical observations of their own, plus Greek and Indian astronomers, allowed them to effectively measure the distance between earthly places or make maps.