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A = pi r^2

Commit this to memory; it is very elementary maths.

Where

'A' is the Area and 'r' is the radius.

In words 'Area ( of a circle) is equal to 'pi' multiplied to the radius squared'.

Similarly for the circumference of a circle.

C = 2*pi*r or C = pi*d

Where 'C' is the circumference of the circle, 'r' is the radius or 'd' is the diameter.

NNB 'pi' ~ 3.14 for elementary school purposes. This is only an approximation for 'pi' as it is an irrational number ; the decimals are in no particular order and go to infinity. Closer approximations are 3.1416 , or 3.141592654....

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Find the circumference of a circle with radius 5 ft.

Area of a circle. The area of a circle of radius r is given by the polynomial πr2. Use 3.14 as an approximation for π.

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28 in long need to know how big to make a circle

Q: How do you find the area of a circle given the radius of a circle?

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By using the other information supplied about the circle to calculate either its radius (from which its area can be calculated) or its area (if the circle is similar to another with a given area and some ratio between the two circle is given):If the diameter is given: radius = diameter ÷ 2If the circumference is given: radius = circumference ÷ 2πIf the circle is similar to another circle which has a given area, and the length ratio is given; square the length ratio to get the area ratio and apply to the given area.

A = pi x radius squared where pi = 3.14

The area of a circle is given by the formula A=pi x r2 Where A is the area of the circle, pi is a constant approximately equal to 3.1415, and r is the radius of the circle. So, to find the area of a circle with a radius of 5cm you would first square the radius -- 25 cm2. Then times by pi. So the answer would be 25pi cm2.

The area of a circle is 153.86cm².find the radius of the circle

Radius = +sqrt(Area/pi)

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If yo have the area of the circle, the square is irrelevant. Radius = sqrt(Area/pi)

The answer depends on what information you are given.

Divide the area by pi and then square root it this will give the radius of the circle.

By using the other information supplied about the circle to calculate either its radius (from which its area can be calculated) or its area (if the circle is similar to another with a given area and some ratio between the two circle is given):If the diameter is given: radius = diameter ÷ 2If the circumference is given: radius = circumference ÷ 2πIf the circle is similar to another circle which has a given area, and the length ratio is given; square the length ratio to get the area ratio and apply to the given area.

Area = pi*radius2 So, radius = sqrt(area/pi)

a=area p=pi r=radius sqr(a/p)=r

Half the square root of the square radius equals the circle radius.

If the circumference or diameter is given then you can find the radius or simply measure the distance from the centre of the circle to the circumference.

A = pi x radius2

A = pi x radius squared where pi = 3.14

If 'R' is the radius of the circle, then-- area of the circle is [ pi R2]-- perimeter of the circle is [ 2 pi R ]

Area of a circle = pi x radius squared, so to get the radius, divide the Area by pi (3.14159), and then find the square root of that

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