Best Answer

use the formula pi*diameter = circumference

and the formula diameter = 2*radius

and combine them 2pi*radius = circumference

now you have a formula that you can just plug you numbers into.

if you have 3 as your radius, then this is how to find the circumference

2pi*3=circumference

6.28*3=circumference

18.84=circumference

Q: How do you determine the circumference of a circle if you know the radius?

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The circumference is twice the radius. In other words, if you know the radius, multiply it by 2 to get the circumference.

Conceptually, the radius is the distance from the center of the circle to any point on its edge. If you know the circumference of the circle, then the radius is the circumference divided by 2 times pi.

Divide its circumference by 2*pi which will give the radius of the circle. Area of the circle then is pi*radius squared

radius = circumference/2*pi

You can either measure it, or calculate it if you know the diameter (radius = diameter / 2), or the circumference (radius = circumference / (2pi)).

Related questions

The circumference is twice the radius. In other words, if you know the radius, multiply it by 2 to get the circumference.

You measure it. If you know the radius (of a circle), you multiply it by 2 to get the diameter. If you know the circumference of a circle, you divide by pi to get the diameter.You measure it. If you know the radius (of a circle), you multiply it by 2 to get the diameter. If you know the circumference of a circle, you divide by pi to get the diameter.You measure it. If you know the radius (of a circle), you multiply it by 2 to get the diameter. If you know the circumference of a circle, you divide by pi to get the diameter.You measure it. If you know the radius (of a circle), you multiply it by 2 to get the diameter. If you know the circumference of a circle, you divide by pi to get the diameter.

If you know the circumference of a circle, you can find the radius by dividing the circumference by the value of Pi (3.14159...)

Conceptually, the radius is the distance from the center of the circle to any point on its edge. If you know the circumference of the circle, then the radius is the circumference divided by 2 times pi.

The circumference of a circle that has a radius of 5 inches is 10 X pi or approximatly 31.415926535897932384626433832795. If you know the radius you can find the circumference by multiplying it by 2(pi)

Divide its circumference by 2*pi which will give the radius of the circle. Area of the circle then is pi*radius squared

Circumference of a circle = 2*pi*radius

36.5 and do you know the answer

radius = circumference/(2*pi)

radius = circumference/2*pi

Circumference = 2 x pi x radius

The answer depends on what information you are given. If you know the circumference, then divide by Pi and that is the diameter. Half of the diameter is the radius. If you don't know anything about the circle, you would need to measure and find the diameter.