An Introduction to Fulati-Suranjan Formulae in Calculating the Area and Perimeter of Any Circle Without Using Pi

In this chapter, an attempt was made to find out the Area and Circumference or Perimeter of Circle, without using Constant Pi, by the Fulati-Suranjan formulae (up to two decimal places) along with a new constant, named Probir's Constant denoted by the Bengali letter roshsho li-kar ৯ . To fulfill these purposes here, have been used some Theorems, Lemmas, Corollaries, the inner circle & the outer circle of the same square, also the inner square & the outer square of the same circle. Since without using pi, this chapter can calculate the area and perimeter of any circle approximately, which have been seen in various examples of this chapter so, claiming here the derived formulae are correct (up to two decimal places). It should be mentioned that a number of papers and online math sites have more or less discussed and proven some form of these theorems, lemma, and corollaries. We believe that readers interested in mathematics, particularly those who are students, will find the approach presented in this chapter to be beneficial. Additionally, it appears that the worried pupils are able to apply and memorize the formulae without the need for the traditional constant pi.