Euler
Leonhard Euler
Pronounced "Oiler" in English, (15 April 1707  18 September 1783) was a pioneering Swiss mathematician and physicist. He made important discoveries in fields as diverse as infinitesimal calculus and graph theory. He also introduced much of the modern mathematical terminology and notation, particularly for mathematical analysis, such as the notion of a mathematical function.
Many differential equations cannot be solved exactly, so we need a numerical method to sketch a solution. Euler's method is one such technique. Interactive calculus applet.
Animation showing that in any triangle, the centroid, circumcenter and orthocenter are always collinear  they always lie on a straight line, called the Euler line.
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