answersLogoWhite

0

Circumference = pi times diameter

or

Circumference= two x pi x radius.

Now remember the diameter of a circle is the straight line from one edge of the circle, through the centre to the opposite edge.

The straight line from the edge to the centre is the radius, and then from the centre to the opposite edge is another radius. So the diameter is the length of two radii.

Algebraically express as d = 2r.

So Algebraically

C = pi*d

Substituting the 'd' for '2r'

C = pi2r

However in algebra coefficient numbers are expressed to the left. Hence

C = 2pir

Why 'C' is this expression I would have to go into some 'very heavy' differential calculus.

Suffice it to say, the ancients found that the circumference traced by a donkey/mule driving water out of well was directly proportional to the diameter, twice the length of the tether(2 radii).

From this they discovered that for however long the the tether and the circumference were. they had a constant of proportion

C directly related to diameter.

This is equated to

C = kd

And

k = C/d , which was founf to be 3.141592..... which now call 'pi'. for any sized circle.

So today in school you learn

C = pi d

or

C = 2 pi r

And for circular area(A)

A = pi r^(2)

The 'pi' youare given in school is proabably 3.14 , 3.1416 or 22/7 . However, these values are Approximatons, because 'pi' is an irrational number.

Hope that helps!!!!!!

User Avatar

lenpollock

Lvl 16
3mo ago

What else can I help you with?

Related Questions

How do you calculate the circumference if you know the diameter?

Circumference is equal to 2 times pi (3.1416) times one half of the diameter (the radius). So, if the diameter is 2 cm, then the circumference would be the product of (2) times (3.1416) times (1), or 6.2832 cm. Circumference is equal to diameter times Pi. c = Pi * d diameter times pi


How do you get circumference when you are given radius?

Circumference is equal to pi x diameter Diameter is equal to 2 times the radius Circumference would be 2 x pi x radius


Why is the circumference of a circle diameter times pi or 2 radius times pi?

Because 2 times the radius is equal to the diameter of the circle


How do you find the circumference of a circle with just the radius?

The circumference of a circle is equal to the radius times 2*pi. 2*pi*R where R is the radius.


How can circumference equal area?

A=pir2 a=3.14(2)2 a=3.14(4) a=pi*d area =pi r 2 circumference=pi times d in this equation in terms of pi, a=csquared


Radius of 5m what is the circumference?

If you mean a circle: the circumference is equal to diameter x pi, or 2 x pi x radius.If you mean a circle: the circumference is equal to diameter x pi, or 2 x pi x radius.If you mean a circle: the circumference is equal to diameter x pi, or 2 x pi x radius.If you mean a circle: the circumference is equal to diameter x pi, or 2 x pi x radius.


What is the circumference of the can?

Circumference of the can is 2*pi*radius or diameter times pi


What is the circumference if the Diameter equals 3 meters?

Circumference is equal to 2 times pi times the radius. The radius is half the diameter, so pi times the diameter is also the circumference. In this case, the diameter is 3 meters so 3 times pi equals 9.42 So the circumference is about 9.42 meters.


How do you use pi to determine circumference?

Circumference = pi times the diameter, or pi times 2 times radius. Area = pi times (radius squared)


How do you get a circumference?

Using a compass and the circumference is measured by 2 times pi times radius or diameter times pi.


What's is the circumference of the circle if the radius is 10 in?

The circumference of a circle is equal to 2 times pi times the radius of the circle. Therefore, if the radius of the circle is 10 inches, the circumference would be 2 times pi times 10 inches, or 20 pi inches. Pi is a mathematical constant with a value of approximately 3.14, so the circumference of the circle would be approximately 62.8 inches.


In order for the circumference of a circle to equal pie what should the radius be?

It is not pie. That is something you eat. It is pi. Your formula is Circumference = pi times Diameter. Diameter = radius times 2. If you replace Circumference with pi then what do you get? You get pi = pi, or 1 pi = 1 pi. or 1=1. You now know the diameter. if the diameter is 1, what is the radius?