1. Pi
By Tracy Hanzal

2. What is Pi?
Pi is the ratio of circumference of a circle to diameter of a circle
The symbol for pi
Circumference
diameter =
Circumference
Diameter

3. The Value of pi
In all circles, the ratio of circumference to diameter results in the same value:
Approximate value:
= ………
Pi is an infinite decimal with no pattern in the decimal value.
Pi may be used to find the circumference of a circle if the diameter is known or to find the diameter if the circumference is known or also to find the area of a circle. Pi is also used in trigonometry in measuring the radians in a coordinate plane.
When approximating the circumference or area of a circle, the value of 3.14 is most commonly used and another value commonly used is the fraction 22/7.

4. History of Pi
There is evidence that the ancient Egyptians and Babylonians were aware of a common value in circles.
The Egyptians figured a value for pi to be 4 x (8/9)2, which is about This value is not very accurate and difficult to work with.
The Babylonians had an easier number to work with. Records show that their value for pi is 3 1/8, which is
Both civilizations approximations of pi are obviously not as accurate as the value we have today, but they knew there was a common ratio and they knew that the value was a little more than three.

5. Computation of pi from 2000 B.C.
More History of Pi
Computation of pi from 2000 B.C.
Who
Year
Value for pi
Babylonians
2000 BCE
3.125
Egyptians
China
1200 BCE 3
Bible (1 Kings 7:23)
550 BCE
Archimedes
250 BCE
3.1418
Ptolemy
150 AD
Fibonacci
1220 AD

6. Symbol for pi Introduced by William Jones in 1706
The Greek Letter Pi was chosen to represent the value …..
The Greek letter, shown at the write is pronounced like our letter “p” which stands for perimeter.

7. Examples Diameter = 6 cm AREA OF CIRCLE = r2
Find the area of the circle:
A = pi x r2
A ≈ 3.14 x (3 cm)2
A ≈ 3.14 x (9 cm2)
A ≈ cm2

8. Examples Volume of a Cone: h = 10 cm V ≈ 3.14 x (4 cm)2 x (10 / 3 cm)
V ≈ cm3
r = 4 cm

9. Works Cited http://www.ualr.edu/~lasmoller/pi.html