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Q: What is the circumference of a circle whose radius is 4.5 in?

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A 45-foot circumference circle has an area of: 161.1 square feet.

141.372 Circumference equals pi times the diameter: 45 x 3.1416 = 141.372 If you memorize the formula, it will serve you well.

First you calculate the circumference of the circle using the standard formula C=pi x D, Where C is the circumference, D is the Diameter of your circle (measured across the widest part of the circle) and pi is a known constant of 3.14 (discovered by the ancient Greeks or is that ancient Geeks?). So if your circle is 300 mm across (12 inches in old terms) then it is calculated as so: 3.14 x 300 = 942mm circumference. To work out the distance between the points you need to decide how many points are required around the circle (circumference). For this explanation I will use 8 points and we know a circle has 360 degrees as seen on a compass therefore divide 360 degrees by 8 points as so: 360 / 8 = 45 degrees. Now the final part to calculate the distance from the first point to the second of 8 points we divide the circumference of the circle 942 mm by 360 degrees to find out the distance of one degree, I hope you are starting to see where I am going with this, as so: 942 / 360 = 2.61666667 mm then you take the answer for 1 degree of the circumference and multiply it by 45 degrees (which is one eight of the circle, giving us the eight points) as so: 2.61666667 x 45 = 117.75mm (or 4.71 inches). Hey presto 'simples' you have the answer! By the way pi is actually 3.14159 and the first people to be aware of such a constant were the Egyptians followed by the Babylonians although their pi's were not as accurate!

(360/45)*Pi*8*8 = (64/8)*Pi = 8*Pi ~= 25.133

It is: 45% of 360 degrees = 162%

Related questions

A circle with a radius of 45 units has a circumference of 282.74 units.

Radius is 45.

32cm, the radius is half of the diameter

The circumference of a circle with a diameter of 45 inches is 141.37 inches.

The diameter of a circle with a circumference of 45 cm is: about 14.32 cm

circumference = 2*pi*radius r = c/2*pi r = 6.28/2*pi r = 0.9994930426 units area of the circle = pi*r2 = 3.138408154 square units

A 45-foot circumference circle has an area of: 161.1 square feet.

divide the circumference (c) by pi (3.14) and then you have diameter. you will have to measure the radius by hand.

If the circumference of a circle is 45 cm the length of the diameter in centimeters is: about 14.32 cm

The radius of a coin with diameter of 45 mm is : 45/2 = 22.5mm The circumference of a coin with diameter of 45 mm is 45*pi = 141,372mm rounded to 3 decimal places

141.37

approximately 141.3

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