What is the circumference?

Pi times the diameter

37.69911

Be sure you're using the correct equation.

Circuference = pi * 12"
= 3.14 * 12
=37.7" (approx)

The radius is half of diameter
d=12 then r = 6
C = 2 x pi x r
C = 2 x 3.14 x 6
C = 37.68 or 37.7

To find the circumference (C): C = Pie x Diameter

So, pie x 12 = approx. 37.7"

Also, area (A): A = Pie x Radius(squared)

The circumference of a circle i equal to Pi x D.

Pi =~ 3.1416

So Pi x D =~ 3.1416 x 12 =~ 37.6991 inches. <<<<<

Side note: It looks to me as if you got this and then multiplied by 3 getting 113". Of course I don't know at what stage of the problem you did the actual multiplication by 3. If you look back at your work, you may be able to find out when you did it and then try to figure out why.

Circumference = (Pi)(Diameter)
C = 3.14 x 12
C = 37.6991
So the circumference of circle with diameter 12 is 37.6991

The circumference of a circle is a little more than 3 times the diameter -- so your answer needs to be a little more than 36 to be reasonable. So you are absolutely right to think your answer makes no sense -- developing common sense is a good thing to have in math, because you know when to look back for mistakes.

There is a formula that will give the circumferences from the diameter for any circle: Multiply the diameter by a special number called pi and the result will be the length of the circumference. That number pi is a little bigger than 3. It is often approximated by 3.14, or more accurately by 3.1416.

So, read this answer twice and do your problem again, without looking at anyone elses work -- that way you will learn it.

Pie X R^2

Here this will help! circle with center point A A circle is a shape with all points the same distance from the center. It is named by the center. The circle to the left is called circle A since the center is at point A. If you measure the distance around a circle and divide it by the distance across the circle through the center, you will always come close to a particular value, depending upon the accuracy of your measurement. This value is approximately 3.14159265358979323846... We use the Greek letter Pi (pronounced Pi) to represent this value. The number Pi goes on forever. However, using computers, mathematicians have been able to calculate the value of Pi to thousands of places.

The distance around a circle is called the circumference. The distance across a circle through the center is called the diameter. Pi is the ratio of the circumference of a circle to the diameter. Thus, for any circle, if you divide the circumference by the diameter, you get a value close to Pi. This relationship is expressed in the following formula: [IMAGE]
C over d equals Pi
where C is circumference and d is diameter. You can test this formula at home with a round dinner plate. If you measure the circumference and the diameter of the plate and then divide C by d, your quotient should come close to Pi. Another way to write this formula is: C equals Pi times d where · means multiply. This second formula is commonly used in problems where the diameter is given and the circumference is not known (see the examples below).

[IMAGE] The radius of a circle is the distance from the center of a circle to any point on the circle. If you place two radii end-to-end in a circle, you would have the same length as one diameter. Thus, the diameter of a circle is twice as long as the radius. This relationship is expressed in the following formula: [IMAGE], where d is the diameter and r is the radius.

C = π d
C = (22/7) 12 ins.
C = 264/7 ins
C = 37 5/7 ins
C = 37.7 ins (to 1 dec. place)