2007-07-23 03:05:13 · 9 answers · asked by kmof6322 1 in Science & Mathematics ➔ Physics
The circumference of any circle is equivalent to the formula C=2pir or C=pid, where r is the radius and d is the diameter. This is true since the radius is half of the diameter. Since pi is equivalent to 3.14 it is used in all unit circle problems (trig) and circle problems in geometry. This number, 3.14, is an approximation that was figured by the mathematicians and physicists of ancient Greece, although the exact person is unsure. A circle, when divided into equal slices and laid side by side resembles a paralellogram. By dividing the circle into more than eight slices, the approximation obtained in this manner would be even better. By dividing the circle into more and more slices, the approximating parallelograms approximate the area of the circle arbitrarily close. This give a geometric justification that the area of a circle really is pi r squared.
2007-07-23 03:21:29 · answer #1 · answered by aspyke13 1 · 0⤊ 0⤋
Pi is just a ratio. You can check this yourself with different sized circles and a measuring tape or ruler.
Measure the diameter. Multiply it by 3.14 (actually, by pi). Write that number down, then measure the circumference. You just verified a mathematical fact.
The circumference of a circle is always, always a bit more than three times the length of the diameter. It's always Pi times bigger, to be exact.
So, if you measure the lengt of your middle finger and it's 3 1/2 inches, then you know that any circle that is that big across is about 7 inches around. Three inches across your fingers? Any circle about that far across is about 6 inches around.
Fast and easy way to estimate circumferences.
Try it with a round swimming pool. A wheel on a truck. Any circle, it'll work.
2007-07-23 10:26:11 · answer #2 · answered by silverlock1974 4 · 0⤊ 0⤋
"Pi" is a constant. It is always the same. It is an irrational number, between 3.2 and 3.7. It is used to calculate the circumference or the area of a circle, or the other way round. It can simply be written using the symbol for "pi" which I, unfortuantely do not have on this keyboard, or it can be given a number value that will be approximate at best.
2007-07-23 10:16:38 · answer #3 · answered by fangtaiyang 7 · 0⤊ 0⤋
Pi is the ratio of the circumference of a circle to its diameter or the ratio between the area of a circle and the square of its radius.
Pi = Circumference/Diameter = Circumference/2*Radius
Pi = Area/Radius^2 = 4*Area/Diameter^2
2007-07-23 10:13:01 · answer #4 · answered by gebobs 6 · 0⤊ 0⤋
pi = area/r^2
pi = circumference * r/2
i think the answer you're looking for is that pi is just a mathematical constant used in certain formulas.
2007-07-23 10:14:00 · answer #5 · answered by Anonymous · 0⤊ 0⤋
(pi) / circumference = half the radius
2007-07-23 10:09:57 · answer #6 · answered by Anonymous · 0⤊ 0⤋
Because it is the first letter of the greek word for "perimeter."
2007-07-23 11:37:18 · answer #7 · answered by Mark 6 · 0⤊ 0⤋
It represents 3.7143569883659599175341546233658845[or infinity]
2007-07-23 10:10:12 · answer #8 · answered by jaime c 1 · 0⤊ 0⤋
the value 3.14.....etc
useful in geometric problems
2007-07-23 10:10:03 · answer #9 · answered by acu04385 2 · 0⤊ 0⤋