History Phi π

Pi has been known for nearly 4000 years-but even if we count the number of seconds in the year 4000 and calculates pi to a number of places, we would still only be closer to the actual value. is a mathematical constant that is the ratio of the circumference of a circle to its diameter. The letter was read Greek alphabet pi and pi can also be used in writing.
Values ​​that are commonly used are 3.14, or yet to be more precise, it sought to> 1,241,100,000,000 decimal places. Values ​​up to 10 decimal places is 3.14159265358.
, Here is a brief history of finding pi:
Ancient Babylon calculate the area of ​​a circle by taking 3 times the square of its radius, which gives the value of pi = 3. One Babylonian tablet (ca. 1900-1680 BC) shows the value of 3.125 for pi, which is a closer approach.
Rhind Papyrus (ca.1650 BC), there is evidence that the Egyptians calculate the area of ​​a circle with a formula that gives an approximate value for pi 3.1605.
Ancient cultures mentioned above found their approach to measurement. The first calculation of pi carried out by Archimedes of Syracuse (287-212 BC), one of the greatest mathematicians of the ancient world. Archimedes approximated the area of ​​a circle by using the Pythagorean Theorem to find areas of two regular polygons: the polygon inscribed in a circle and polygon in which the circle was circumscribed. Since the actual area of ​​the circle lies between the areas of the inscribed and circumscribed polygons, the area of ​​a polygon provide upper and lower limits for the area of ​​the circle. Archimedes knew that he did not find the value of pi but only an approximation within those limits. In this way, Archimedes shows that pi is between and.
A similar approach is used by Zu Chongzhi (429-501), a brilliant mathematician and astronomer China. Zu Chongzhi will not be familiar with Archimedes' method-but because his book has been lost, little is known of his work. He calculated the value of the ratio of circumference of a circle to its diameter to be. To compute this accuracy for pi, he always started with an inscribed regular 24,576-gon and performed lengthy calculations involving hundreds of square roots carried out to 9 decimal.
Mathematicians began using the Greek letter π in the 1700s. Introduced by William Jones in 1706, the use of this symbol popularized by Euler, who adopted it in 1737. The 18th century French mathematician named Georges Buffon devised a way to calculate pi based on probability. You can try yourself in the Exploratorium's Pi Toss exhibit.
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