Person: Ibrahim Ibn Sinan
Ibrahim ibn Sinan was an Islamic mathematician and astronomer who studied geometry and in particular tangents to circles. He also made advances in the theory of integration.
Mathematical Profile (Excerpt):
- Ibrahim's most important work was on the quadrature of the parabola where he introduced a method of integration more general than that of Archimedes.
- Ibrahim is also considered the foremost Arab mathematician to treat mathematical philosophy.
- We know of Ibrahim's works through his own work Letter on the description of the notions Ibrahim derived in geometry and astronomy in which Ibrahim lists his own works.
- For example Ibrahim uses an arithmetical term to denote the product of two geometrical lines.
- In On the measurement of the parabola Ibrahim ibn Sinan gives a beautiful proof that the area of a segment of the parabola is four-thirds of the area of the inscribed triangle.
- It also provides a critical analysis of the observations underlying Ptolemy's solar theory, and Ibrahim ibn Sinan provides his own theory of the sun.
- Ibrahim proves in this work that the stereographic projection maps circles which do not pass through the pole of projection onto circles.
- Examples are given which illustrate how Ibrahim applied an orthogonal compression to transform a circle into an ellipse, and an oblique compression to map a hyperbola into a second hyperbola.
- In a different work Ibrahim uses a transformation which maps figures keeping invariant the ratio between their areas.
Born 908, Baghdad, (now in Iraq). Died 946, Baghdad, (now in Iraq).
View full biography at MacTutor
Tags relevant for this person:
Ancient Arab, Astronomy, Origin Iraq
Thank you to the contributors under CC BY-SA 4.0! 
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- @J-J-O'Connor
- @E-F-Robertson
References
Adapted from other CC BY-SA 4.0 Sources:
- O’Connor, John J; Robertson, Edmund F: MacTutor History of Mathematics Archive
