Finding the area of a circle sector.?
468719
Use A = 1/2(r^2)theta (radians).  The sector formed by the radius from the origin to (sqrt2,sqrt2) and the radius from the origin to (2,0) has an angle of 45 deg.  The sector formed by the angle of the radius from the origin to (sqrt3,1) and the x-axis has an angle of 30 deg.\n45 deg. - 30 deg, = 15 deg or pi/12 radians.  The area is (1/2)(r^2)pi/12 = pi(r^2)/24 for any sector with a central angle of pi/12.  Since r^2 = 4, A= 4pi/24 = pi/6.
146689
to find the area of a circle.pie r squared.r being 1/2 dia.
860968
u can use the following formulas to find the radius\n1)Area of circle=pi.*(radius)^2\nwhen area is given plug in that value into this formula and u can get the radius\n2)radius=diameter/2\nwhen the diameter is given,find the radius by dividing the diameter by 2\n3)circumference=2*pi.*r\nwhen the circumference is given use the above formula to solve for the radius\n\nthere is no definite formula for the radius but depending the other value given u can solve for the radius.\nhope that helps!!!
52227
area of a circle is Пr2. hit the П key (shift -> exp (if you have a casio)).  the radius is 9.  square the radius. 9x9=81 (Пx81 or Пx9x9 = 254.4690049 <- that is your answer)
1048814
If the circles are concentric, just subtract the area of the smaller circle from the larger circle:\n\nArea of small:  6*6*pi\nArea of large:  9*9*pi\n\nDifference of areas = 81*pi   -    36*pi  =  45*pi = 45 * 3.14159  = \n\n141.37 square units
1060915
Area can be calculated by using the formula Area = 4 Pir^2 .  You didn't mention radius of the tank, thus a numerical answer is impossible.
952353
The curved surface area is 2*pi*r*h\n\nor 2*3.142*27*12 sq cms\n\nand 2*3.142*17*35 sq mms\n\nyou can do the rest
953741
Just break the pentagon up into 5 triangles.  You can then add together the area of the 5 triangles to get the total area.
135768
Area = Pi times the radius squared (A=pr2)\nIf you need to know how to find the radius, go here:\n\nhttp://math.about.com/library/blcircle.htm
572270
triangle area = 1/2(height * width)\n\ncircle area = pi * radius^2
1071211
area of circle is pi*r^2, so A=pi*40,000*t
820614
So am I answering a homework question for you? lol\n\nCircles have the minimal perimeter for the area contained.\nArea of a circle is pi x Radius x Radius. (pi R squared)\n\nNext best would be something close to a circle, so consider a hexagon or octagon, with the corners of the square intersecting the vertices of the outer figure.\n\nLet's try a circle first...\n\nDiameter of the circle would be the diagonal of the square, or five times the square root of two.  5 x 1.414 = 7.07.  So the Radius is 3.535 meters.\n\nPi x 3.535 x 3.535 = 3.14 x 12.5 = 39.34\n\nSo the circle solution is too big.\n\nNow work out on paper what an octagon or hexagon surrounding the square would look like.  One of those should be about 34 m square.  Remember the area of the square is already 25 m2, so you are looking for only 9 more m2.\n\nI played around for minute or so in paint, and came up with a parallelogram that worked too.  Finally, a smooth curving perimeter shape get you benefits similar to the "circle" solution, so an ellipse would be a good comparison solution.  Try that, and compare the perimeter result against the perimeter of the parallelogram, which has a perimeter of 24.23 meters.\n\nHave fun!\nOC
877943
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!!
863802
area=(1/2)d1*d2\n=(1/2)*28*13\n=14*13\n=182 sft
668236
Simple algebra, just rearrange the equation.\n\nYou obviously know the formula for the area of a circle:\n\nA = pi r²\n\nSo solve this for r as follows:\nDivide both sides by pi\nA/pi = r²\n\nTake the square root of both sides\nsqrt(A/pi) = r\n\nSo plug in your value of A = 50.24 and solve\nr² = 50.24 / 3.14159 = 16\nr = 4
625973
How to do this problem:\n1. Find the Radius. To do this, take the diameter and divide by two. This gives you a radius of 5.\n2. Because the Area of a circle is equal to Pi times the radius squared, and your teacher wants the answer in terms of pi, square the radius and get 25 pi.
136253
You're already on a website.  What is it with people these days?  Look in your book.  \nInteresting though: the derivative of the area of a circle is equal to the circumference of it.  Works the same for a sphere too.