The Importance of πin Circles
The irrational numberπ(which is spelled “pi” and pronounced
“pie”), is a key concept when working with circles. Pi is essential to calcu-
lating the area of circles as well as the circumference—the perimeter
around the outside—of a circle. Over 2,000 years ago Greek mathemati-
cians discovered that πis actually the never-changing quotient of the
cirdciuammefetreernce. This ratio is the same in all circles, and although piis an irra-
tional number that continues infinitely, the most commonly used approxi-
mation for πis 3.14.17
Circumference and
Area of Circles