I assume you want to find the area of a circle?
Let p = pi = 3.14, r = radius, d = diameter, a = area and c = circumference.
a = pr2
a = pd2/4, where r = d/2
a = c2/4p, where d = c/p
Circumference = pi*d. So d = Circumference/pi
Divide the circumference by 3.14159265 (3.14 for rough approximation) to find the diameter of a circle.
Divide the circumference by the value of Pi - that will give you the diameter.
Radius = Circumference/(2*pi)
To find the area of a circle knowing only the circumference, you can use the formula A = (C^2) / (4π), where A is the area and C is the circumference. Square the circumference, then divide it by 4π to get the area.
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.
C = 2pi * r
If you know the diameter and need the circumference you times the diameter of the circle by 3.14 also known as pie. That is how you get the circumference by only knowing the diameter. :)
Circumference of a circle: pi times diameter
To find the circumference of a circle, you need only know the radius or diameter of the circle. The circumference of a circle is calculated as 2 x Pi x radius OR Pi x diameter. Pi is approximately 3.1415926.
to find the diameter of a circle when you only have the circomference you: divide the circomference by pi (approx. 3.14)
The equation for finding the circumference of a circle is diameter times pi so reverse it to circumference divided by pi which leaves the diameter. The diameter is twice as big as the radius so divide the diameter by 2 and you will find the radius.