en.wikipedia.org/wiki/Pi

The number π is a mathematical constant, the ratio of a circle's circumference to
its diameter, commonly approximated as 3.14159. It has been represented by ...

www.mathsisfun.com/numbers/pi.html

circle radius=1, half circumference=pi. Draw a circle ... is 3.14159265... a number
known as Pi ... pi symbol. Pi (the symbol is the Greek letter π) is: The ratio of the ...

mathforum.org/dr.math/faq/faq.pi.html

What is pi ( )? Who first used pi? How do you find its value? What is it for? How
many digits is it? By definition, pi is the ratio of the circumference of a circle to its ...

wonderopolis.org/wonder/what-is-pi

Pi is the ratio of a circle's circumference to its diameter. ... Most geometry students
first encounter pi when they study circles and learn that the area of a circle is ...

www.livescience.com/29197-what-is-pi.html

Apr 30, 2013 ... Pi represents the ratio of the circumference of a circle to its diameter. Pi is an
irrational number that never ends; the decimals go on forever and ...

eduplace.com/math/mathsteps/6/g/index.html

Pi. There are many fascinating numbers in mathematics. One of the most
interesting number relationships that students can discover in geometry is that
the ratio ...

wiki.c2.com/?ValueOfPi

Seriously, it does make sense to define "pi" as a defined constant - not because
... The text states, "the ratio of the diameter and circumference is as five-fourths to
...

www.math.com/tables/constants/pi.htm

Pi is a name given to the ratio of the circumference of a circle to the diameter.
That means, for any circle, you can divide the circumference (the distance around
...

setosa.io/ev/pi/

The last line in the article is pointing out that we could've just as easily have used
the ratio C/R (circumference over radius) in the place of pi in almost every ...

www.mathworks.com/help/matlab/ref/pi.html

This MATLAB function returns the floating-point number nearest the value of π.