2007-05-01 03:06:18 · 16 answers · asked by Sandy M 1 in Science & Mathematics ➔ Mathematics
PI!
C = Pi * D
Where Pi = about 3.1415926536...
2007-05-01 03:09:21 · answer #1 · answered by Jerry P 6 · 0⤊ 0⤋
The diameter multiplied by pi is equal to the circumference.
Pi is a special number that is defined as the ratio between the diameter and the circumference of a circle. It is irrational, that is to say after the decimal point its digits go on and on and on forever without ever either stopping or repeating (this has been proved mathematically). Pi is approximately equal to 3.1416, although if you want to see the first million digits of pi you can go here:
http://3.141592653589793238462643383279502884197169399375105820974944592.com/index1.html
Yes, that's a real website. And no, the URL is not a million digits long.
2007-05-01 10:18:39 · answer #2 · answered by Anonymous · 0⤊ 0⤋
The formula for a circumfrence of a circle is C [meaning[circumfrence] = pi[d]. Okay, d = diameter. Or radius, [half of the circle] times two. I can't make the symbol for pi, but if you type it in on Google or Yahoo it is sure to come up. It looks like two lines, somewhat slanted with a squiggly over it. Plug in your formula with numbers. Whatever the diameter is takes the place of d, and approximations for pi are 3.14 or 22/7. Good luck! Anyone who says it is pirsquared are wrong, that is the AREA of a circle.
2007-05-01 10:18:31 · answer #3 · answered by soccer2star 2 · 0⤊ 0⤋
The circumferance of a circle is calculated by the formula "2 x pi x radius"
Now diameter = 2 x radius
So, the formula for finding the circumferance of the circle if you know the diameter is pi x diameter.
2007-05-05 09:37:07 · answer #4 · answered by Anonymous · 0⤊ 0⤋
1) Either use a string to measure it physically, OR
2) Draw 2 chords on the circle.
Construct the perpendicular bisectors of the 2 chords.
These perpendicular bisectors will meet at the centre of the circle.
Draw a line across this centre from one side of the circle to the other - this is the diameter.
Measure the diameter.
Circumference = pi x diameter
2007-05-02 21:51:47 · answer #5 · answered by Kemmy 6 · 0⤊ 0⤋
Here's an example:
The diameter of a circle is 3 centimeters. What is the circumference?
Solution:
C = pi * d
C = 3.14 · (3 cm)
C = 9.42 cm
2007-05-01 10:13:27 · answer #6 · answered by Anonymous · 0⤊ 0⤋
Circumference = 2 (Pi) r = (Pi) D
r = radius, D = diameter, (Pi) = 3.142
Just multiply the diameter by 3.142
If D = 1 then the circumference = 3.142
If D = x then the circumference = 3.142 x
2007-05-01 10:23:34 · answer #7 · answered by BB 7 · 0⤊ 0⤋
The formula for calculating the circumference of a circle is 2Pi R .R is the radius which is half the diameter .So the equation would 2X 3.1416xR.
2007-05-01 10:31:18 · answer #8 · answered by Anonymous · 0⤊ 0⤋
C = Ïd where d is the diameter.
Example
Calculate circumference when radius = 5 m
d = 10 m
C = (Ï d) m = (Ï x 10) m = 31 . 4 m
2007-05-01 17:52:18 · answer #9 · answered by Como 7 · 0⤊ 0⤋
Pi times the Diameter = Circumference. For Pi use 3.14159 and you will be close enough.
2007-05-01 10:14:19 · answer #10 · answered by Sounds of Ed's football game 3 · 0⤊ 0⤋
circumference = pi x diameter
Take pi as 3.142 for most exam questions.
Diameter 5cm Circumference = 3.142 x 5 = 15.7cm correct to 3significant figures
2007-05-01 10:14:04 · answer #11 · answered by fred 5 · 0⤊ 0⤋