why is the angel at the center of a circle twice that at the circumference?
406803
Angels usually stay outside of circumferences, where only fools rush in.
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 :)
881999
It is half the size of a full circle.\n\nArea of a full circle = pi r²\nArea of a semi-circle = (pi r²) / 2\n\nIf you mean the perimeter, it would be half the circumference, but you'd have to add the diameter as the length of the flat side.\n\nCircumference of a full circle = pi d\nPerimeter of a semicircle = (pi d)/2 + d
553186
twice the distance from the middle to one end
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.
655789
The main question you are asking is why are there 360 degrees in a circle.  A right angle is 1/4 of the circle (with 4 right angles), that is why you get 90 degrees.\n\nAs to why there are 360 degrees in a circle, the answer lies in the fact that the ancient Babylonians used the   sexagesimal system (i.e., their base was 60 rather than 10).\n\nThe Babylonians also discovered that the perimeter of a hexagon inscribed in a circle is exactly equal to six times the radius of the circumscribed circle.  This was evidently the reason why they chose to divide the circle into 360   degrees and therefore why a right angle is 90 degrees.\n\nThis has no relationship to slope which is really just a percentage.  A slope of 8% is 8/100 or 8 feet change vertically for every 100 feet horizontally.  Obviously percentages are from per-cent (per 100 or 1/100).  Since we now use a base 10 system, this makes sense.  1/90 would not.
766220
If its distance from the center is less than the radius, it's inside.\n\nYou can find the distance from the center using your handy pythagorean theorem.
366583
This is because of their centre of gravity.\n\nAll of their constituent mass is  pulled with an even force into the centre of the object....thus the surface of the celestial body is equidistant from the centre...ie. almost spherical.\n\nMany are in fact oval due to the fact that they spin around. This moves some of the mass to the equator of the object....rightly due to centrifugal force.
428953
Pentagons occur naturally when tying knots due to the same reason that when strings are pulled taut, and a fret is placed in the middle, that the pitch that it plays on either side of the fret is a 'perfect fifth.' The idea is that the knot is exactly half the distance away from its other side within the knot itself. If one wants to see how this happens naturally, all you have to do is draw a five-pointed star, turn the page 180 degrees, and then draw another five-pointed star the others middle. This can be done ad infinitum inward or outward until physics prevents it from occurring. \n\nThe irony is: the perfect fifth is not what makes music music per se, rather it is the diminished fifth, the tri-tone, or so called devil's tone that makes music capable of changing keys from one to the next. Though, the reason that this happens is due to the natural harmonics that occur in the environment, that make the diminished fifth the actual additive center (where the perfect fifth is its multiplicative one) from the root to the octave. Knowing these two sets of mathematics and where they overlap, eerily\ncan define pretty much any physical phenomena from the Relative to the Quantum. (Unfortunately, there are very peculiar rules that establish how the sets occur whose overtones include concepts such as inverses, opposites, paradigm, zero, and the infinite.) And chances are that disarming your knots will probably find us an answer to the Zeta function. Good luck!\n\nOn a side note: it was Pythagoras who (is ironically famous for someone anonymous' theorem) started a cult around the idea of the perfect fifth, which eventually made the pentagram the infamous symbol that it is today. But this was not until after, he was murdered by a band of math conscious rioters who decided his cult was evil because they had been hiding the existence of the irrational numbers, which exist due to the multiplicative tendencies of an additive system of measurement.\n\nThat's all for which I have time.
601593
Circumference is the distance around a circle.  2 times pi ( which is about 3.14) times the radius (the distance from the center of the cirle to any side).  In formula form it looks like this C = 2*Pi*r.\n\nThe formula for area of a circle is A = Pi*r^2 ( also known as r squared)
1165642
One way to reason is this.  Let n be any even integer greater than or equal to 4.  Divide the circle into n equal wedges (by drawing n/2 diameter lines with angles between successive lines equal to 360/n degrees).  Now, cut the wedges out and make a "rectangle" with them: n/2 wedges with the points downward and the arcs on top of adjacent pairs of wedges touching each other, then the other n/2 wedges with the points upward and adjacent arcs touching, filling the spaces of the first n/2 wedges.  What you end up with is almost a rectangle with top and bottom each made of n/2 360/n-degree arcs, and the lateral sides slanting slightly, made from the long edges of the wedges on each end.\n\nYou can estimate the area of this figure (which is the same as the area of the original circle of radius r) by pretending it IS a rectangle.  The length is the circumference of the circle, or 2*pi*r/2 (since half the circumference is the top, half is the bottom) (by definition of pi).  The width is the length of a wedge, or r.  So the area is about pi*r^2.  \n\nTo turn the estimate into an exact value, consider what happens as n goes to infinity, that is, it increases without bound.\n\nAs n goes to infinity, the slanted edges aproach being verticle and the number of arcs making up the top and bottom approaches infinity, and the arcs themselves approach straight horizontal lines.  Thus, the figure approaches a rectangle of exactly area pi*r^2.  However, for each n, you have the same circle of the same area, so the area of that circle is pi*r^2.
385118
the circumference divided by 2 x PI
389938
The equation of a circle with the center at the origin is \nx^2 + y^2 = r^2 where "r" represents the radius of the circle\n\nTherefore the equation of a circle with the center at (0,0)and radius 10 units would be\n\nx^2 + y^2 = 10^2\n==> x^2 + y^2 = 100\n\n\nhttp://www.schoolingkids.com/\n\nhttp://www.futureaccountant.com/
239617
A circle consists of all the points on a plane equidistant to a single point (the center.)\n\nIt's mathematical formula is:\n\ny = sqrt(r^2 - x^2) \nwhere r = radius and the center is at origin.
483599
the other answers are somewhat correct but unnecessarily long....\n\n1. the rainbow is actually a circle that is partially visible as an arch due     \n    horizon limitations.\n\n2.  it is a circle because the light source ( the sun ) is a circle.
927299
It means "2 times pi times r" (where r is the radius of the circle)
90686
I´m guessing you want to know the difference in meaning, since you already have the values.\n\nThe radius is the distance measured from the center to the edge of a circle. Imagin Earth as an orange cut in half and put back together. The cut line would be the Equator. Now open the orange and face the inside of the orange and you´ll see a white circle. The distance from the center of the orange to the edge (or white stuff) is the radius.\nThe circumference (or perimeter) is the length of one full lap around that circle.