Then the circumference (all the method around the circle) is 3.14159265...

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a number known as Pi

Pi (pronounced like "pie") is frequently written making use of the greek prize π


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The definition of π is:

The Circumferencedivided by the Diameterof a Circle.


The circumference separated by the diameter the a one is always π, no matter how huge or little the circle is!

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To help you psychic what π is ... Just draw this diagram.


Finding Pi Yourself

Draw a circle, or use something circular favor a plate.

Measure roughly the leaf (the circumference):

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I got 82 cm

Measure across the one (the diameter):

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I obtained 26 cm

Divide:

82 cm / 26 cm = 3.1538...

That is quite close come π. Probably if i measured an ext accurately?

Using Pi

We can use π to find a Circumference as soon as we know the Diameter

Circumference = π × Diameter


Example: you walk about a one which has actually a diameter the 100 m, how much have girlfriend walked?

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Example: Sam measure 94 mm around the outside of a pipeline ... What is the Diameter?


Radius

The radius is fifty percent of the diameter, so we can likewise say:

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For a circle through a radius that 1

The distance half way about the circle is π = 3.14159265...


Digits

π is around equal to:

3.14159265358979323846…

The digits go on and also on v no pattern.

π has been calculation to end sixty sunshine decimal places and also still over there is no patternto the digits


Approximation

A quick and also easy approximation because that π is 22/7

22/7 = 3.1428571...

But as you have the right to see, 22/7 is not precisely right. In reality π is no equal to the ratio of any two numbers, which makes it one irrational number.

A really good approximation, far better than 1 part in 10 million, is:

355/113 = 3.1415929...(think "113355", slash the center "113/355", then flip "355/113")

Summary:

22/7=3.1428571...
355/113=3.1415929...
π=3.14159265...

Remembering The Digits

I usually simply remember "3.14159", but you can likewise count the letter of:

"May I have a huge container the butter today"3 1 4 1 5 9 2 6 5

To 100 Decimal Places

Here is π through the first 100 decimal places:


Calculating Pi Yourself

There are countless special approaches used to calculation π and here is one you can shot yourself: that is referred to as the Nilakantha series (after an Indian mathematician who lived in the years 1444–1544).

It walk on for ever and also has this pattern:

3 + 42×3×444×5×6 + 46×7×848×9×10 + ...

(Notice the + and also − pattern, and additionally the sample of numbers below the lines.)

It gives these results:


TermResult (to 12 decimals)
13
23.166666666667
33.133333333333
43.145238095238
...... Etc! ...

See more: How Many Cm In 42 Inches ? Convert 42 Inches To Centimeters


Get a calculator (or usage a spreadsheet) and also see if you have the right to get better results.


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Pi Day

Pi work is commemorated on march 14. March is the 3rd month, so the looks favor 3/14


Activity: uncover an Approximate worth For Pi
one Radians Annulus Irrational Number