ABSTRACT
René Descartes is famous for his philosophical saying, ‘I think, therefore I am’, yet he was, as many clever men of the seventeenth century were, a great all-rounder. His intellectual skills also encompassed mathematics and, in particular, geometry. In 1636 he published his work on algebraic methods for geometry. He used the x-, Y-, z- coordinate frame he had created as a foundation on which algebraic geometry could be used. The coordinate system based on the x-, y-, z- axis system is called, after him, the Cartesian coordinate system. The idea came to him while lying ill in bed. ‘I saw a fly climbing the wall and thought - How can I specify the fly’s location unambiguously in such a way that others can understand me?’ The French mathematicien and philosopher René Descartes (1596–1650) https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315069555/5d5201a7-70ac-4d14-a96d-80b2cf916e2e/content/fig0137.jpg"/> https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315069555/5d5201a7-70ac-4d14-a96d-80b2cf916e2e/content/fig0138.tif"/>
