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
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!
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):
Measure across the one (the diameter):
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?
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:
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 + 42×3×4 − 44×5×6 + 46×7×8 − 48×9×10 + ...
(Notice the + and also − pattern, and additionally the sample of numbers below the lines.)
It gives these results:
| 1 | 3 |
| 2 | 3.166666666667 |
| 3 | 3.133333333333 |
| 4 | 3.145238095238 |
| ... | ... 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.
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