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JordanA = 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 = 2pir 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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How do you find the area of a circle when the radius is unknown?
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.
What is the formula to find the area of a circle with the radius given?
A = pi x radius squared where pi = 3.14
What is the radius of a circle if the area is 153.86cm2?
To find the radius of a circle when given the area, you can use the formula A = πr^2, where A is the area and r is the radius. Given that the area is 153.86 cm^2, you can plug this value into the formula and solve for r. 153.86 = πr^2 r^2 = 153.86 / π r = √(153.86 / π) ≈ √49 ≈ 7 cm Therefore, the radius of the circle is approximately 7 cm.
If the area is 628 what is the radius of a circle?
To find the radius of a circle with a given area of 628, you can use the formula for the area of a circle, A = πr^2, where A is the area and r is the radius. Rearranging the formula to solve for the radius, you get r = √(A/π). Substituting the given area of 628 into the formula, you get r = √(628/π) ≈ √(199.87) ≈ 14.14. Therefore, the radius of the circle is approximately 14.14 units.
How do you find the area of a cirlcle?
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.
