radius is R \nDIAMETER IS D\nCircumferen is C\nCircumferen of a cicle
126619
Use the well known formulas that relate the radius and diameter of a circle to its circumfrence.\n\nC = pi * D\nC = 2 * pi * R\n\nFor pi, you can use 3.14 or 22/7, or whatever value your teacher wants you to use.
574541
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
26274
If its a circle inscribed within a triangle then the largest will be the incircle of that triangle... the radius of which is given by: (area of triangle)/semi-perimeter...\nsemi-perimeter(s) = (a+b+c)/2\narea of triangle = square root of[s(s-a)(s-b)(s-c)]\na, b, c -> are the sides of the triangle...\n\nonce u know the radius u can calc the area of the circle...
76407
The distance around it.The circumference.
355272
if you know radius, it is 2 time the radius times 3.14 (2*r*Pi), if you know diameter, its is diameter times 3.14 (d*Pi)
40820
d= {R/ x=4}\nall real numebrs, except x= 4
467844
I expect the answer is surface.\n\nA sphere has circumference, too.  But the thing is that a circle encloses a two-dimensional space, and the circumference is the boundary of that space.  Well, a sphere encloses a three-dimensional space, and the thing that encloses that space is the surface,  or surface area if you're thinking in terms of measure.
511230
It means "2 times pi times r" (where r is the radius of the circle)
39562
Diameter will be 1 units\n\nCircumference =piD\nif Circumference =pi\nthen D=1
123590
Think of the first as the area of a flat round plate sweeping out the inside of the figure you get from the rotation.  What will be its area? πr² where the r is the y value of √(9 + X²).  That changing area will sweep out the volume from whatever the limits are (you don't say), so it's the integral of π(√(9 + X²))², or π(9 + X²).\n\nIn the second case, the thing sweeping out the volume is the surface area of a cylinder as its radius grows.  Thats the circumfrence of the base times the height.  The circumfrence is 2πr where r is the X value and the height is the difference between Y = x and Y = X/2.  So it's the integral from 0 to 2 of:\n\n   2πX(X-X/2).\n\nThinking of an area sweeping thru the volume helps.
391437
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.
444193
I haven't done one of these in quite a while. \n\nWhat would you differential element be?  How about r*(dtheta)*dr?\n\nthat sort of a ds*dr   where ds depends on the radius.  Try it! \n\nNote that without the sin theta you'd get the int rdthetadr with r 0 to R and theta 0 to 2pi  You'd get the correct area of a circle.\n\nTry the intergral, see if it makes sense.  Then sketch the figure and estimate it's area to compare.  My confidence is increasing as I write this.
510572
The diameter of the circle is the diagonal of the rectangle (as the angle in a seicircle is always 90°)\n\nDiameter = 2 * radius\n= 10 cm\n\nSo by Pythagoras' rule\n\nx² + 8² = 10²\nx² = 100 - 64\n= 36\nx = √36\n= 6\nSo other side is 6 cm
167921
well that question cant be answered b/c only a circle has a radius nothing else
403039
dC/dt = 4 m/s\nC = 2*PI*R\ndC/dt = 2*PI*dR/dt = 4\nSo dR/dt = 2/PI\n\ndA/dt = d(PI*R^2)/dt = 2*PI*R*dR/dt = C*dR/dt = 32 * 2/PI = 64/PI m/s
218865
well, ok, i see lots of complicated answers...but here is the answer in simple terms\n\nthe radius measures teh distance from the center to its boundry...it doesnt matter what the coordinates of teh boundry are because we have to use the distance formula to find it which is\n\nd = sqrt[(x-x1)^2 +(y-y1)^2]\n\nso from this equation (x1,y1) is the origin (0,0)\n\nso you really have\n\nradius = d = sqrt[x^2 + y^2]\n\nso whatever point you choose the distance must be positive because any numbers squared then added will be positive.\n\nso you would claim, well what if the center wasnt at the origin, well the only difference would be that you would use the original distance equation i mentioned.\n\nSo we can say that all distance (according to the distance equation) must be positive, try it with any points you like, it will always be positive.  Due to the distance equation always being positive, all radii must be positive.\n\nhope this helps\n\nmatttlocke\n\nPS\nand for everyone who says distance cant be negative...they lie\n\nthe magnitude of direction can never be negative the negative does imply direction.  for example, on the number line, we have points -5, and 5, the distance of both of those points from 0 is 5, but if we were plot each point they would be going in opposite directions, and we know this due to the negative sign\n\nso the distance formula means that the distance will always be positive, the negative does tell you direction, ask any mathematician (im working on that) or a physicist and they will tell you the same thing.\n\nBut, a negative and positive radius mean the same thing because the boundry of the circle will intersect all the points at whatever the measure of the radius is in all directions, so i spose you could look at it as negative, but it doesnt really matter.  This would all hold in any 'n' dimension.
474327
volume of cyllinder = area of circle times height\n\n= Pi x radius x radius  x height\n\nremember its just the same as finding the volume of any prism.\nfind the area of the shape of the end then multiply by its length!!