Divide the 81 pi by pi, then square root it. (Use the formula for area of circle, which gives 81pi=pi*radius squared, but rearrange to find the radius). i.e. it's the square root of 81
Using 3.14 as Pi the area of circle is: 2.5434
radius = sq rt of (81/pi) = 5.077706252 diameter = 2*077706252 = 10.1554125 inches
The area of a circle is equal to πr2 where π (pi) is equal to approximately 3.142 and r represents the radius of the circle. Because the question gives you the diameter and not the radius you have to use the measurement of the diameter to calculate the radius. Remember that the radius is equal to half the diameter. So if the diameter is equal to 18 feet, then the radius of this particular circle is equal to 9 feet. Plugging this into our equation for area we get: area = π(92) area = 3.142(81) area = about 254.5 ft2 (don't forget that the answer is in squared feet not just feet)
Area= pi × radius2 Area= 3.14 × (4.5 in2) Area= 3.14 × 20.25 Area= 63.585 in2 The answer is 63.585. You would find this answer by doing this: 20.25 x3.14 _______ 8100 20250 +607500 _______ 635850 Then you would take the zero off the end.
Area of circle: 81*pi square feet
The area is 9 feet. You find the square root of 81 which is 9. I want circumference, not area.
Area of a circle of radius r = πr2Area of circle of radius 9 In = π(9)2 = π x 81 , putting value of pi we get= 3.14159625 x 81 = 254.46 sq. In
Area(A)/ Area(B) = pi*rA2/pi*rB2 = rA2/rB2 = 16/81
Radius 10, area = 100 pi; radius 9, area = 81 pi
Area= pi x radius squared. So radius (9) squared = 81, 81 x 3.14. See related link for more info.
i believe that it is 18 if the radius is 9 edit: wrong, area = pi*radius^2 so it's 3.1415926535*81=254.469
Area of a circle with radius r = pir2Area of the largest circle = Area of the smallest circle + Area of the shaded regionSince areas of the smallest circle and the shaded region are 9pi and 72pi, the Area, A, of the largest circle isA = 9pi + 72pi = 81pi, where r2 = 81.Thus, the radius of the largest circle is 9
648pi. (pi = 3.14159...)Area of a circle = (pi) x (radius squared)= (pi)(9 squared) = (pi)81.Area of a cylinder = area of circle x height.= (pi)81 x 8= 648(pi)
Using 3.14 as Pi the area of circle is: 2.5434
To find area of a circle, the formula is πr2 where π is pi. Half of the diameter is the radius (r) so you divide 18 by 2 to get the radius (9). then, you square it (multiply it by itself) giving you 81. You then multiply this by pi to get the area. The exact answer is 81π, with a good approximation of: 254.46900494077325231547411404563973361997072134938357149897
radius = sq rt of (81/pi) = 5.077706252 diameter = 2*077706252 = 10.1554125 inches
pi*radius squared = 81 square units Divide both sides by pi and then square root both sides to find the value of the radius. radius = 5.077706252 or 5 units in length to one significant figure 2 times radius = diameter = 10 units in length