en.wikipedia.org/wiki/Pi

The number π is a mathematical constant, the ratio of a circle's circumference to its diameter, ... The symbol used by mathematicians to represent the ratio of a circle's circumference to its diameter is the lowercase Greek letter π, sometimes ...

www.angio.net/pi/whypi.html

Pi (π) is the ratio of the circumference of a circle to its diameter. ... Archimedes used this trick with 96 sided polygons to correctly estimate Pi to about two digits ...

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

Apr 30, 2013 ... Pi (π), the 16th letter of the Greek alphabet, is used to represent the most widely known mathematical constant. By definition, pi is the ratio of the ...

curtiscenter.math.ucla.edu/content/pi_applications

Dr. David H. Bailey, co-discoverer of the Bailey–Borwein–Plouffe formula for pi, guest authored this post. Many presume that π is only used for geometric ...

www.newyorker.com/tech/elements/pi-day-why-pi-matters

Mar 13, 2015 ... They're calling this the Pi Day of the century: 3.14.15. ... memorized these and similar formulas for the S.A.T.s and then never again used them, ...

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

What is Pi? Who first used Pi? How do you find it? What is it for? How many digits is it?

www.tulsaworld.com/business/fyibusiness/pi-common-in-everyday-life-not-just-dessert/article_d1e06850-b460-5ea6-8417-29bed2386234.html

Mar 14, 2014 ... Well, it turns out we see Pi being used in business and everyday life all the time. Whether it's the pipes running beneath your feet or the power ...

www.reference.com/math/pi-used-5fba050fbb78ef3d

Pi is used to find the circumference and area of a circle. It is also used to find the volume and surface area of a sphere, cone and cylinder. Pi has applications ...

www.mathsisfun.com/numbers/pi.html

Pi (π). pi circle diameter. Draw a circle with a diameter (all the way across the circle) ... There are many special methods used to calculate π and here is one you ...

wonderopolis.org/wonder/what-is-pi

The Greek letter π was first used to represent pi by William Jones in 1706, because π was an abbreviation of the Greek word for perimeter: "περίμετρος." ...