The circumference C is pi times the diameter of the circle, which is twice the radius
C= pi *2r
The area A is pi times the radius squared
A = pi r2
where pi = about 3.14159
Example:
For a radius of a 3 cm
C = pi x (3 x 2) = pi x 6 = about 18.85 cm
A = pi x (3)2 = pi x 9 = about 28.275 cm2
To find the circumference of a circle then multiply pi (3.14159265...) by the diameter of the circle. To find the area then multiply pi by the radius squared.
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.
You neglected to say whether the 4mm is the radius of the circle, or the diameter,or the circumference. Each possibility leads to a different area.
They would have to give you enough information to eventually get the diameter. If they gave you the area of a circle and asked for the circumference, you can determine the radius, and from the radius the diameter, and then the circumference. If they said "What is the circumference if the area of a circle is 36pi?" Area of a circle is pi*r2, which would give us a value for r = 6 Diameter is 2*r, or = 12. Circumference is d*pi, or 12pi
First find the radius by dividing the circumference by 2pi which works out as 16 units. Area = pi*radius2 Area = 256pi square units
Circumference of a circle = 2*pi*radius or diameter*pi Area of a circle = pi*radius squared
To find the circumference of a circle then multiply pi (3.14159265...) by the diameter of the circle. To find the area then multiply pi by the radius squared.
Divide its circumference by 2*pi which will give the radius of the circle. Area of the circle then is pi*radius squared
The radius of a circle is the distance from the center to any point on the circle. The area is the space within the circle. The formula to find the area is πr2. r stands for the radius of the circle. If you want to find the radius, you can work backwards from the area or the circumference, which is the perimeter of the circle. The formula for circumference is 2πr.
Circumference = 2*pi*radius Area = pi*radius2
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.
Area of a circle = 3.14 * r2 Thus, radius, r = root of ( Area of a circle / 3.14 ) --------- equation 1 Circumference of circle = 2 * 3.14 * r Therefore, from (equation 1), Circumference = 2 * 3.14 * root of ( Area of a circle / 3.14 ). In a nutshell, first find the radius and then the circumference.
you divide the area by pi. then, find the square root of the number you have. now you have the radius. find the circumference by multiplying by the diameter or by multiplying by two times the radius.
if it is the radius you can find area or circumference
2 x pi x radius = circumference pi x radius squared = area
Using the circumference, you would find the radius first. The circumference C = 2*Pi*r where r is the radius. Then, the area of the circle = Pi*r^2.
Square root (Area/pi) to get the radius Then 2xRadiusxPi= Circumference