# Pi Day! March 14th

3.1415926535 8979323846 26433832….. You know Pi. Pi day is march 14th and I will teach you some things about Pi. Not Pie but Pi.

## Vocabulary Words

Pi; 3.1415926535 8979… or round it and use 3.14.

Circumference: The distance around a circle or sphere.

Diameter: From one side of the circle to the other side.

Radius: From the center of the circle to circumference. (1/2 Diameter)

Now that we are done with vocabulary, I will teach you how to find area, circumference, and volume of 3 shapes.

## Equations

Area. The formula for area is π r2″ Square the radius and then multiply 3.14.

Circumference. The formula for Circumference is “2πr” Square pi to 6.28 and multiply by the radius.

Volume of a Sphere. The formula is “4/3 πr3″ cube radius multiply by  3.14 then multiply by 4/3

Volume of a Cylinder. The formula is πr2h” multiply the area by the hight.

Volume of a Cone. The formula is “1/3πr2h” a cone is just 1/3 of a cylinder.

## History

Pi was first used in Egypt and Babylon. But the symbol we use today is greek. The first equation was by Archimedes. Before Pi people did not understand circle’s.

## Other Assorted Facts

Pi is an Irrational number, which means it never ends.

It is ironic that you use pi to find a ton of things with circles but pie commonly is a circle.

Pi=c/d or circumference/ diameter.