? is one of the most important mathematical and physical constants: many formula from mathematics,science and engineering involve ?.We use this value as 3.1459 or may be 3.146, but ever thought how we get it or what was its value when it originated ? Here comes the answer of all your questions.The Greek letter ?, often spelled out pi in text, was adopted for the number from the Greek word to find the circumference, or perimeter, of a circle.The first value that was devised for pi was 3 ! strange but it’s a fact (around 600 BC ).
Although there were many who made rigorous attempt to quantify pi but Archimedes was the first to give a rational expression to his calculation. He started with the theory that value of pi can be approximated by inscribing a polygon in a circle and then keep on increasing the sides of polygon.
Later around 250 AD Indian and Chinese proved that its value could be calculated by an iterative approach. He himself carried through the calculation to a 3072-gon and obtained an approximate value for pi of 3.1416.
Well the history goes very much there with as many as 100 of mathematicians evolved in its calculation
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