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Given that the circumference of any circle is 2 * pi * r, where pi is the mathematical constant (~3.14) and r is the radius, solving for the radius is quite simple.
we'll call the circumference c:
c = 2*pi*r
divide both sides by 2*pi:
c/(2pi) = r
and then the diameter is just 2 * radius.
Area = pi*(r)^2 = pi*(c/(2*pi))^2 = (c^2)/(4*pi)
(~ denotes approx. value)
Quick example:
So if a circle has a circumference of 30cm:
30 cm= 2 * pi * r
r = (30cm)/(2*pi)
r = (30cm)/(2*3.14) = ~4.78 cm
diameter = 2 * ~4.78 cm = ~9.56 cm
area = (30 cm)^2 / (4* ~3.14) = ~71.66 cm^2
c = 30 cm, r = ~4.78 cm, d = ~9.56 cm
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How do you find the diameter and then the circumference if you have the radius?
Diameter = radius * 2 Circumference = pi * diameter.
How do you find the circumference from the area?
Well, you find the area of a circle by multiplying (pi times radius2) or (pi times radius times radius). The radius is half of the diameter. The formula for the circumference is (pi times diameter). Multiply the radius times 2 to get the diameter. Multiply the diameter times pi.
How can you find the diameter and the radius if the circumference is given?
Diameter = circumference/pi Radius = circumference/2*pi
Find the circumference and the area of a circle with radius?
Circumference = pi (3.14) times the diameter (radius times two) Area = pi (3.14) times the radius squared
What number is in the circle to find radius and diameter?
There are four common measurements of a circle, radius, diameter, circumference, and area. Here is how they are related. Diameter is how far across it is at the widest point. Radius is 1/2 of diameter. Diameter X pi = circumference. pi = 3.1416 Area = pir2
