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Eratothsenes Follow the link to his very cool project
The Ancient Greeks - and they got it right, which was more than Columbus did!
The Greek mathematician Eratosthenes calculated the circumference of the Earth fairly accurately over 2300 years ago!
Eratosthenes was the first person to do this. He measured the distance netween two points and the different angles mad by the Sun - and worked out from these. His result was surprisingly accurate.
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When would you want to find the circumference of a circle?
The first step to calculate circumference of a circle is to know the formula. There are two formulas that can be used for the purpose. They are:Circumference of a circle formula 1: C = π x diameterCircumference of a circle formula 2: C = π x 2 radiusHere are a few illustrations that would make problem solving related to finding the circumference of a circle easy:Using the Radius:If the value of the radius is known then it can be put in the 'circumference of a circle equation' already mentioned and the value calculated. For example:Given that the radius of circle is 3 cm.Circumference of the circle: C= π x 2 radiusor, C= 3.14 x 2 (3) cmor, C= 18.84 cmUsing the Diameter:If the value of the diameter is known it can be directly put in the 'circumference of a circle equation' and the circumference calculated. For example:Given that the diameter of a circle is 6 cm.Circumference of the circle: C= π x diameteror, C= 3.14 x 6 cmor, C= 18.84 cm
What is the circumference of a circle with an area of 144 pie sq in?
To find the circumference of a circle with an area of 144π sq in, we first need to find the radius of the circle. The formula for the area of a circle is A = πr^2, where A is the area and r is the radius. Given that the area is 144π sq in, we can solve for the radius: 144π = πr^2, r^2 = 144, r = 12 inches. The circumference of a circle is calculated using the formula C = 2πr, so for a circle with a radius of 12 inches, the circumference would be 24π inches.
If the circumference of a circle is 32pi what is the area of the circle?
First find the radius by dividing the circumference by 2pi which works out as 16 units. Area = pi*radius2 Area = 256pi square units
What is the circumference of a circle if its radius is 14cm?
First, we should note that the formula for circumference is Dπ, or diameter times pi. Second, we should note that the diameter is simply double the radius. With this in mind, the circumference formula can then be turned into (2r)π C=2(14)π C=28π which is about equal to 87.96459
What is the circumference if the area is 379.94 cm square?
The first step is to work out the radius. The formula for area is pi(r2). That equals 379.94, so plug this into the equation and you get a radius of 10.997. The formula for the circumference is pi(2r). Plug the now known radius in and you get 69.097516968554117299881726353374 Therefore the circumference, if the area is 379.94cm2, will be 69.1cm
