# What is PI, a.k.a. "π" ?

What is “PI”, and what is its significance? PI, designated by the Greek letter π, is a mathematical constant defined as the ratio of a circle’s circumference to its diameter. This Circumference/Diameter ratio used to calculate π is depicted below:

Often approximated fractionally as 22/7 or rounded to 3.14159, π is an irrational number that cannot be represented with terminating or repeating decimals.

In engineering and construction, understanding π is of critical importance, as it is impossible to build various structures and building features without measuring or controlling critical diameter or circumference dimensions.

Aussie World Ferris Wheel^{1} (upper left); Leaning Tower of Pisa^{2} (upper right);

St. Peter's Basilica^{3} (lower left); Izumo Dome^{4} (lower right).

In building the Exodus Tabernacle Courtyard curtain set, the same basic understanding of π or PI (approximately equal to 314/100) is also required, as illustrated in the sketch below:

Next Page: Ancient PI (π)

References

1. By Softeis (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/)], via Wikimedia Commons

2. By Aussie world (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 4.0-3.0-2.5-2.0-1.0 (http://creativecommons.org/licenses/by-sa/4.0-3.0-2.5-2.0-1.0)], via Wikimedia Commons

3. Giacomo della Porta [Public domain], via Wikimedia Commons

4. https://www.flickr.com/photos/kentamabuchi/3511199478/in/photostream/