Born a Jew in Barcelona, I became a mathematician, astronomer philosopher...and also a Chief of Police.
A pupil of Rabbi Moshe haDarshan and a teacher of Abraham Ibn Ezra, I also dabbled by writing texts in astronomy and geography...and wrote papers on astrology, trigonometry and music.
I wrote all my works in Hebrew, making me the recognized pioneer in the use of the Hebrew language for scientific purposes.
I am most proud of my text Ḥibbūr hameshīḥah wehatishboret ("Treatise on Measurement and Calculation"), which not only focuses on algebra and practical geometry, but also contains the first complete solution of the quadratic equation x^{2}  ax + b = 0 known in Europe.
My work influenced the work of Leonardo Fibonacci.
Using the geometricmechanical method of indivisibles, I proved the area equation for any circle: S = LxR/2, where S is the area of the rectangle, L is the circumference of the circle, and R is the radius of the circle.
Answer:
Abraham bar Ḥiyya (1070 – 1136 or 1145)
