History of pi

History of pi

What is pi???

 If it is the question, then there are different answers.

  firstly, pi is the ratio of the circumference and radius of a circle of any radius.

   It is also obvious that pi is an irrational number.

    Actually pi a mysterious number of mathematics; a special constant.

  There are many stories about the discovery of pi.

  History of pi

  Pi was  seen for the first time  200 years before the birth of Christ. Pi was used in the old Babylon. Then the  value of pi was 3.125. The Rhind Papyrus informs that in around 1600 BC Egyptians used 3.1605 as the value of pi.

  The person who had found  the value of pi for the first time mathematically was the great greek mathematician Archimedes.

    It was in around 250 BC. The value of pi given by him was greater than 3.1408 and less than 3.1429.

   After 400 years later  another greek philosopher Tolemy  had shown that pi=3.14166.( He told that a circle has 360 sides).

  In the third AD  Liu-Hiu from china, calculated the value of pi upto five decimal places.  400 years after his work another Chinese mathematician Zu Chong determines the value of pi upto six decimal places.His pi lies between  3.1415926 and 3.1415927.

 The Indian mathematicians had thought about pi differently. Around 1400 AD Indian mathematician Madhava had calculated pi correct upto 11 significant figures, using a series( now known as Gregory series).

The value of his pi was given by:

   π/4= 1-1/3 + 1/5 - 1/7 + 1/9 -...

  (This series is obtained from Gregory series and better known as Leibniz series.)

  Before Madhava another great Indian Brahmagupta in 640 AD had obtained pi=√10. It is assumed that a Chinese Zhang Heng  in 130 AD had obtained the value of pi √10 400 years before Brahmagupta.

  In the Christian 9th century Muhammad - Al - Khwarizmi had calculated pi upto 4 significant figures. After many years Jamshid - al- Kashi had found the value of 2π correct upto 16 significant figures.

  In 1701 the value of pi correct upto 100 decimal places was given by  John Machin.

  In 1781 Swedish mathematian Johann Lambert proved that pi is an irrational number.

 In 1873 William Shanks had highlighted the value of pi upto 527 decimal places.

 Point to be noted that French mathematian Faancosis Viete first expressed pi as a product of infinite terms as:

 2/π=√1/2×√1/2+1/2×√1/2...

  John Wallis also expressed pi as a product of infinite terms.

  There were many people in the entire world who had viewed pi differently.

 Till now pi is not known comptely. 

   Actually,  pi is an endless mysterious number!!!
     

 If you find out any incorrect information or know anything more about this , please write it in the comment section!