Other math breakthroughs of the 12th century

Although Fibonacci is said to have contributed the most to the math realm during the 12th century, there were some other additions provided by different mathematicians. One was scholar Abraham bar Hiyya, a Jewish mathematician who contributed in the areas of algebra and geometry. Hiyya is famous for his equation for area of a circle.
A=.5*L*R where L is the circumference and R is the radius.

Another important contributor was Omar Khayyum, a Persian mathematician. He is most well-known for solving cubic equations, and realizing they can have more than one solution. He did this using conic sections. The use of algebra would not be applied to these equations until later. He also wrote commentary on some of Euclid's postulates. He was able to prove that Euclid's definition of equality of ratios, and the earlier definition proposed by Islamic Mathematicians were equal to each other.

Lastly, another scholar was Nasir al-Din al-Tusi, also a Persian mathematician. He is credited with being the first person to separate the study of trigonometry from astronomy, and give it its own branch of mathematics. One famous law he is credited with is The Law of Sines for Plane Triangles.
a/sinA=b/sinB=c/sinC where a,b,c are the side lengths and A,B,C are the corresponding angle measurements.

 

http://www.mathwarehouse.com/trigonometry/law-of-sines/formula-and-practice-problems.php

Sources:
O'Connor, J. J. "Area of a Circle by Rabbi Abraham Bar Hiyya Hanasi." Area of a Circle by Rabbi      Abraham Bar Hiyya Hanasi. N.p., n.d. Web. 21 Mar. 2014.

O'Connor, J. J. "Nasir Al-Din Al-Tusi." Al-Tusi_Nasir Biography. N.p., n.d. Web. 21 Mar. 2014.

"Omar Khayyam." Khayyam Biography. N.p., n.d. Web. 21 Mar. 2014.