What is pi (22/7) ?

Question

What does this number actually represent .. I know we use it a lot in circle area and parameter calculations , but what is it actually ?

Answer 1

The mathematical constant π is an irrational real number, approximately equal to 3.14159, which is the ratio of a circle's circumference to its diameter in Euclidean geometry, and has many uses in mathematics, physics, and engineering. It is also known as Archimedes' constant (not to be confused with an Archimedes number) and as Ludolph's number.

In Euclidean plane geometry, π is defined either as the ratio of a circle's circumference to its diameter, or as the ratio of a circle's area to the area of a square whose side is the radius. The constant π may be defined in other ways that avoid the concepts of arc length and area, for example as twice the smallest positive x for which cos(x) = 0

Answer 2

22 7 Pi

Answer 3

pi is an irrational number, its actual number is defined to an innumerable amount of decimal places. It is a number which decribes the relationship (ratio) between the circumference of a circle and the diameter.

It's usually rounded to 3.14 or 3.1415, or in the case of this question you've asked, 22/7

This means that the circumference of a circle is approx. 3.1415 times more than the diameter.

it's just a number, really.

if you google it, you can find websites dedicated to listing millions of digits of pi.

Answer 4

It's just a rational number that is close enough to pi to be useful. For kicks, take your calculator and find the ratio of this approximation to pi.

22/7 = 3.1429
pi = 3.1416

ratio is 1.0004, which is very close, don't you think?

Answer 5

This Site Might Help You.

RE:
What is pi (22/7) ?
What does this number actually represent .. I know we use it a lot in circle area and parameter calculations , but what is it actually ?

Answer 6

When you have 7 feet diameter circle the circumference of the circle is approximate 22 feet.which means for 1 feet diameter the circumference of the circle is 22/7 feet which is 3.14.(pi x D)

Answer 7

(m)

The first famous "pi people" in history were probably the very first people on the planet. They saw circles everywhere: in other people's eyes, the Moon, the Sun, etc. In order for these people to make the first step in determining pi, however, they had to understand the concept of magnitude. For example, the bigger a stone is, the heavier it is. The smaller the stone, the lighter it is. From these simple observations, prohuman then had to realize that some things have direct proportional relationships. He had to look at a circle and think, "The wider a circle is 'across', the longer it is 'around.'" From this, a very profound statement would be, "No matter how long or wide a circle is, the relationship between them is always the same."

The first cultures given credit for finding a value of pi are the Babylonians and the Egyptians. In the year 2000 B.C.E., the Babylonians determined that pi is equal to 3 1/8 and the Egyptians arrived at 4(8/9). Both got these values, probably, by drawing a circle in the sand and measuring the distance around it with a rope. That point on the rope is then marked and then the distance across it is measured. To determine pi, the person would have to see that the circumference is about three times the length of the diameter, with a little bit left over. Obviously, it's impossible to tell just by looking that the little bit is really approximately .1415926535897932384626433832795028841971693993751058209749445923078164062862099, so the 1/8 (.125) that the Babylonians came up with is not very far off for that time period.

Another early record (1650 B.C.E.) of pi is located on the Rhind Papyrus, written by a scribe by the name of Ahmes. On the papyrus are 84 math problems and their solutions, though it doesnít say exactly how the solutions were found. Ahmes writes that the area of a circle with a diameter of 9 is the same as a squareís area with a side of 8 units. With the formula A=r^2, the Egyptian value of pi becomes =4 x 8/92, which is 3.16049. Other problems on the papyrus show the first attempts to build a square with the same area as a circle.

In the 3rd century B.C.E., Archimedes of Syracuse tried another method of squaring the circle. He drew a circle and inside the circle he draws a hexagon. From the hexagon, he constructed more and more sides on to it until arriving at a a polygon with as many sides as he could fit. With a 96 sided polygon, he figured out that pi is greater than 3.140 but less than 3.142. He arrived at those values without trigonometry (let alone a calculator). Astounding!

The next major "digit hunter" of our story is Leonardo de Pisa in 1220, otherwise known as Fibonacci. He is well known for the Fibonacci sequence


1, 2, 3, 5, 8, 13, 21, 34, 89, 123...

where each number is the sum of the two numbers before it. He used Archimedes's method of the 96-sided polygon, but having the advantage of square roots he calculated pi to 3.141818. Another breakthrough came in 1593 when François ViÈte found a formula to describe pi. Though he is famous for the formula, he also used the Archimdedean method to determine the correct first 10 decimal places of pi by using a 393,216 sided polygon.

It wasn't until 1761 that Johann Heinrich Lambert proved that pi is indeed irrational, but that doesn't stop anyone from finding more than what is known. Today, it is not the best mathematician who can calculate pi but the person with the fastest computer and the right software. The Joy of Pi Website as well as many others will display over a million decimal places in a matter of seconds.


Why Pi?


This may be quite shocking, but the Greeks never used to mean what it means today! That's right! Even though pi itself is a Greek letter, the Greeks thought of it as just that. Pi has only been widely recognized as the symbol for the ratio of circumference to diameter for the past 250 years. 17th century mathematician William Oughtred was probably the first to use pi to mean any number. In 1652, he used pi to stand for circumference in a constant proportion to its diameter, but never used one symbol for that ratio. In 1689, a Bavarian professor J. Christoph Strum used the letter e to represent what we know as pi. For another hundred years, most other mathematicians were still using notations such as c/d.

The very first use of pi as 3.14159... appeared in William Jones' Synopsis palmoriorum matheseos in 1706. Without warning, it appeared as follows: There are variouis other ways of finding the Lengths or Areas of particular Curve Lines, or Planes, which may very much facilitate the Practice; as for instance, in the Circle, the Diameter is to the Circumference as [his infinite series] = 3.14159, =



This book was not nearly as influencial as Leonhard Euler's (OIL-er's) work, which made famous for what we know it to be today.



How Can I Calculate Pi?
And, duh, of course I know there's a button on my calculator!

is transcendental, meaning it is not the solution to any algebraic equation, even though it is, theoretically, a ratio. Conveniently, calculators are programmed to measure angles in radians, which are 180/pi (about 57) degrees. This means that you can get to pi by pressing inverse cosine -1. Euler came up with two more prolific ways to get to using trigonometry:
METHOD 1: 4[5arctan(1/7) + 2 arctan(3/79)]
METHOD 2: 4[2 arctan(1/3) + arctan (1/7)]
Both of these are based on the fact that the tangent of /4 radians is 1.

PI can be approximated through infinite series with the help of calculus.

Answer 8

22/7 is a good aproximaton of π. Slightly better than 3.14
22/7-π=0.00126448926734961868021375957764
3.14-π=-0.0015926535897932384626433832795029

Answer 9

22/7 is 3.1429

Answer 10

It's the ratio of the circumference to the diameter of a circle.
(Thought I'd leave my answer plain 'n' simple since everyone else posted a lot already.)