The circumference of a 40 mm circle is: 126 mm
get the circumference of the circle using 2*pi*r (1.2*pi) times that by 40 to get the answer (48*pi)
Circumference is 2 x pi x r = 3.14 x 2 x 20 = 3.14 x 40 ='125.6 cms
For a given area a circle has least perimeter. eg Let area = 100 sq cms. For the square or rectangle the perimeter = 40 cms For the circle the radius is square root of 100/3.1416 = 5.64 and the circumference = 2 x radius x 3.1416 = 35.44 cms
About 40 feet. Circumference = 3.14 x diameter
radius = 40/(2*pi) in inches
Circumference of any circle = 2*pi*radius or diameter*pi
251.2 feet
40 ft
1256 inches ++ Another Answer ++ The formula for finding the Circumference of a circle is C = Pi x D where D is Diameter and Pi is 3.1416. The Radius of a circle is one-half of the Diameter, hence the Diameter of a circle with a 20-inch Radius is 40 inches. Using the formula above, multiply 40 x 3.1416 to find the Circumference: 40 x 3.1416 = 125.664 inches.
In order to even discuss this question, we must assume that the unit of the '40' is the square of the unit of the '4'. -- The radius, diameter, and circumference of the circle with an area of 40 are each 10.794% shorter than the corresponding measurement in the circle with radius = 4 . -- Its area (40) is 20.423% less than the area of the circle with the radius of 4 .
The formula to figure out the circumference of a circle is C=2(pi)r. So with a circle that has a radius of 40 inches, you can set up the formula like: C=2(pi)40. To figure this out on a calculator, multiply 2 with pi and then multiply that answer with 40. If you do not have a pi symbol on your calculator you can multiply 2 with 3.14159 then multiply that answer with 40.
The circumference of a 40 mm circle is: 126 mm
Radius: 40/2pi = 6.366197724 Area: pi*6.366197724 squared = 127.324 square feet rounded
Circumfrence is 2 times pi times the radius 6.3 x 2 x 3.1415 39.5829 approximately 40
Diameter: Well, you said it yourself, 80 feet. Diameter is the distance across the widest part of a circle. Radius: The radius of a circle is half of the diameter, so in this case, it would be 40 feet. The radius is the distance from the center of the circle to the outside. Circumference: The formula for circumference is Pi (3.14 or 22/7) times the diameter. In this case, it would turn out to be 251.2 feet. Area: The formula for the area of a circle is Pi time the radius squared. So, you square the radius and multiply that by Pi (3.14). In this case, it would be 15775.36 feet squared. I hope I made sense. :)
Radius = 40 m implies circumference = 2*pi*40 = 251.3 m approx.