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By Tracy Hanzal

Pi. By Tracy Hanzal. 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. The Value of pi. In all circles, the ratio of circumference to diameter results in the same value:

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By Tracy Hanzal

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  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: = 3.14159265359……… 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 3.16045. 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 3.125. • 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

  6. Symbol for pi • Introduced by William Jones in 1706 • The Greek Letter Pi was chosen to represent the value 3.14159….. • The Greek letter, shown at the write is pronounced like our letter “p” which stands for perimeter.

  7. Examples AREA OF CIRCLE = r2 Diameter = 6 cm Find the area of the circle: A = pi x r2 A ≈ 3.14 x (3 cm)2 A ≈ 3.14 x (9 cm2) A ≈ 28.26 cm2

  8. Examples Volume of a Cone: h = 10 cm V ≈ 3.14 x (4 cm)2 x (10 / 3 cm) V ≈ 3.14 x (16 cm2) x (10 / 3 cm) V ≈ 167.467 cm3 r = 4 cm

  9. Works Cited http://www.ualr.edu/~lasmoller/pi.html http://math.forum.org/dr.math/faq/faq.pi.html http://www.cecm.sfu.ca/project/ISC/Pihistory.html http://www.equationsheet.com/eqninfo/Equation-73.html

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