Can some explain the the theory of Pi in detail to me please?  And Don't say 3.14 or Pi=r2?
536388
Pi is the ratio of the diameter to the circumference of the circle.  Circumference = PI x diameter.\n\nThe arabs were the first to use it: they had a very good approximation at 22/7
1135397
I think Circumference=pir2 (or pi times the radius squared)
587235
E = energy, M = mass, C = the speed of light\nPi = 3.14159265353589793238462643383279502884197169399375\nSo much for the numbers as there are many more, Pi enables the identification of all that was and ever will be. It is an accountants and mathematicians tool.\nIt is also a noun in that it is the Greek translation of the Egyptian Hieroglyph which describes the Crystal Magnetite. Magnetite is a double pyramid, isometric. Play with the crystal in the palm of your hand, you can feel the energy that powers the soul.\nPhysically it is '1' unit. It sides number eight (8) the symbol for infinity. All sides form a triangle, the mark of the Trinity. The degrees of the angle are 60 and 3 - 60s' are 180 degrees. Two pyramids faces North and South encompass 360 degrees which is full circle, another symbol of infinity. Four faces North and four faces South with a base of a square. Pi X the Radius squared = the circumference. Geometric it is the triangle the square and the circle. The Triangle and the square are recognizable but the circle is not. It is the mind that must fill in the void. E = R I is always presented in the pyramid. E = Voltage, R = resistance & I = amppreage.\nNo electrical device can exist without one of the three. Magnets are a electrical energy source, Loadstone is the dust of magnetite. Magnetite is likewise greater than Uranium as a power source in that it is not harmful to our well being and the world in which we inhabit. It is in fact what the Universe is, and that is Energy (electrical), & Gravity. The flow of the magnetic wave is seen in the flux between the north and the south and it exist through the mechanism of the helix; as in DNA spiral. \nYes, Pi = infinity is Heaven. It is one third antimatter. Antimatter, It is the Resistance of the Formula E=RI. Alternating current is the Antichrist. It is God and it is not Religion. God is a three letter word it is the Trinity. GOD is everywhere, it is in your blood and all that is you. Fe3, O4 atomic wt. 144.24, All the numbers have multipole meanings. It is a wiseman who understands.
215612
C = 2 pi r\nif d = 24.2, r = 12.1\n\ntherefore C = 2 x pi x 12.1\n            = 76.03\n\nFor all the guys think i shud get a keyboard whacked on my head i explained how it shud be worked out and didnt just giv d answer. \n\nInstead of saying rubbish i suggest u at least confirm that my answer is correct!!
92491
OK, first off no one seemed to be able to answer the dividing by 0 and 1 issue correctly, so here goes...\n\nDivision by n is defined as multiplication by the multiplicative inverese of n.  The multiplicative inverse of n is defined as the number 1/n such that n*(1/n)=1.  Zero has no multiplicative inverse because 0 times anything is 0.  Therefore division by zero implies multiplication by a number that does not exist.  One does have a multiplicative inverse (1x1 = 1), so division by 1 is perfectly valid, although you are correct that the result is the number which was divided by 1.  It is exactly the same as multiplying by 1.\n\nNow on the area of a circle issue...\n\nYou seem to be trying to relate area to circumferance.  It's not hard.\nLet A = the area of the cirlce, c = the circumferance, and r = the radius.\nYou already know that A=(pi)r^2 and c=2(pi)r.\nSolve the second equation for r and get r=c/(2pi).\nNow substitute that into the first equation to get A=(pi)(c/(2pi))^2.\nThen simplify and you get A=(c^2)/(4pi).\n\nLike it or not, you can't get rid of the pi.  Pi is defined as the ratio of the diameter of a circle to its circumference, so it's going to be there no matter what.  When you say it's useless unless you know all the digits, this simply isn't true.  Depending on what you're doing, you can either get the pi's to cancel out, or you will be finding a decimal approximation of the area or circumference.  If the radius is a whole number, the area simply won't be (there may be a few values for which it will be, but most of the time it isn't), and any formula you come up with that says otherwise is incorrect.\n\nAs for the sphere question, I don't understand what you're asking.  Are you trying to equate area to volume?  They're not the same thing.  You can't find the area by sticking together infinitely thin slices as the slices have no height so you will never have a third dimension.  You might be able to do it using limits, but that's not going to be the kind of nice simple numbers you're looking for.  If you can explain what you meant, I might be able to do a bit better.
443040
I don't know why 4 of the 8 answers so far say it's true. It's false.\nOne of them reversed the inequlity, and so gave the wrong answer.\ne=2.71828182845905\npi=3.14159265358979\n\ne^pi=23.1406926327793\npi^e=22.459157718361\n\ne^pi < pi^e is false\nChecking to 510 decimal places won't change the result.
255897
The gentleman above has the formulas correct  but to finish your question pi=3.14 so 2pi would be 6.28
386304
this is exactly the same as a previous question asked about an hour ago. Look back on the open questios, your answer is there\n\nh = 100/pi*r^2\n\nh=7.96
63950
In math, Pi (no 'e') is the ratio of the circumference of a circle to its diameter. The ratio is the same for all circles and is approximately 3.1416. The actual number is pretty much never-ending...the exact number has been calculated to over 200 billion digits...most of which looks like this:\n\n3.141592653589793238462643383279502884197169399...
482997
because the definition of pi is the ratio of a circle's circumference to its diameter, or \n\npi = circumfrance:diameter\n\nthis ratio always equals 3.14.... , it's a constant
838513
Sigh - first guy had it right, but didn't explain it all.  \nPi = 3.14- all you need for the problem\nRadius= half the diameter of your circle. You find the midpoint and measure from there to the side of the circle, in any direction. Most problems give you the radius. or at least show you the midpoint on the circle.\n\nSo, it is 3.14 x the amount of the radius x 2= the area of the circle.\n\nYou can do this in reverse as well, if you know the area but not the radius.
927299
It means "2 times pi times r" (where r is the radius of the circle)
236568
Pi is indeterminate.  It keeps going on forever.  Here is the beginning:\n\n3. 14159 26535 89793 23846\n\nThe last link is supposed to list the first 50,000 digits.  I didn't check to see if it was right :).
1018456
r = d(pi)/180\nd = r(180)/pi\n\n\nr = -0.00923157  pi = 3.1415\n\nd = (-0.00923157)(180) / 3.1415\nd = -0.528929999
543735
A crude approximation to pi. The Babylonians had a better one 355/113 which is 3.141592
855373
it goes around the circle twice, therefore it is a coterminal angle to the original angle.  all trig values are the same.  the only difference is that the degrees goes up by 720.\n\nadding or subtracting multiples of 2 pi just go around the circle.  since pi=180 degrees, add or subtract 180*the number of pi's.  \n\nyummy pumpkin pie :)
636151
Doing paper work you often use the ratonal approximation 22/7 = 3.1428.. However pi is irrational and can't be represented exactly as the ratio of two integers. pi goes on forever and has no repeating decimal pattern. But a better approximating ratio is 355/113 = 3.141592...