The formula for the circumference of a circle is c (perimeter) =2πr (radius) or C=πd (diameter). Where π is pi and has a fixed value, generally π=3. 14. Calculation method of circle circumference =πx diameter C=πxd.

π stands for π

π, ranked 16 in the Greek alphabet, is the first letter of Greek π ε ρ ρ ε ρ α (meaning boundary and circumference). Although it existed as early as four ancient civilizations, π has really been redefined as a universal constant for only nearly 300 years.

According to historical records, 163 1 year, π first appeared in the book "Keys to Mathematics" by mathematician William Oughtred. 1706, the British mathematician William Jones also mentioned π in his math textbook Introduction to New Mathematics.

However, at this time, the demand for π estimation is still in short supply, and it did not attract the attention of mathematics until Euler was met.

1748, Euler's masterpiece Introduction to Infinitesimal Analysis was published. In this book, Euler suggested using the symbol "π" to express pi, and directly used π in it.

Under the active advocacy of Euler, π finally became synonymous with pi.