We know that the one is a collection of point out in which every the points are equidistant indigenous the center suggest (O).

You are watching: What is the relationship between diameter and circumference

The circumference of a one is its border or the length of the finish one of a circle.

The diameter the a circle is a straight line authorized a point from one finish of the circle to a suggest on the other end of the circle, passing v the center.


In this quick article, we will certainly learn about the relationship in between the circumference and also the diameter of the circles.

Lesson Plan

1.What Is expected by Circumference to Diameter?
4.Important note on Circumference indigenous Diameter
5.Solved examples on Circumference native Diameter
6.Thinking the end of the Box!
7. Practice inquiries on Circumference native Diameter

Meaning that Circumference come Diameter

The one of a circle is concerned its diameter.

If you recognize the diameter (d)of a circle, then you deserve to easily find the one (C) using the relation: (C=pi d).

So, when the circumference (C) is placed in ratio with the diameter (d), The price we acquire is (pi).

In fact, right here comes the standard definition of(pi) together the proportion of circumference and also diameter of a circle.

What Is the general Formula To calculate Circumference come Diameter?

Formula for Circumference

The circumference of a circle deserve to be calculated using theradius(r)of the circle and also the value of (pi).

Circumference of the circle = (2 pi r)

While making use of this formula, if we do not have the value of the radius, us can discover it making use of the diameter.

That is, if the diameter is known, it deserve to be separated by 2 to attain the worth of the radius because:

Diameter the the circle = (2r)

Another way to calculation the one of a circle is by utilizing the formula:

Circumference of the circle = ( pi imes) Diameter

How To use Formula To calculation Circumference from Diameter?

To calculate the one of a one shape once the diameter is offered we must use the formula for circumference.

< extCircumference=pi imes d>

Let's recognize the ide with the assist of one example.

Jason wants to repaint the outer boundary of a circularswimming pool.

He knows that the diameter the the swimming pool is (50mathrm;feet).

To calculate the quantity of paint required he demands the circumference of the pool.


Let's help him to calculate the one of the pool.

Use the formula because that circumference ( extCircumference=pi imes d) whereby (d) is the diameter of the pool.

<eginaligned extCircumference&=pi imes d\&=pi imes 50\&=50endaligned>

Therefore the one of the pool is (50pi).

Circumference Calculator

Let's try the listed below simulation and see just how the size of the circumference changes with the diameter.


Important Notes
(pi) (Pi) is a mathematical consistent which is the ratio of the circumference of a circle to its diameter. The is approximated to (pi=dfrac227) or 3.14.We can find the circumference of a circle making use of the radius or diameter.The circumference (C)and diameter (d) of a circle are connected as (C=pi d).

Solved Examples

Example 1

Michael has actually a one park that diameter 21 feet in front of his house.


He wants to fence the park.

He wants to know the length of the rope compelled for fencing.

Can you help him?


The diameter that the park is(d=21; extfeet).

To uncover the size of the rope, we will need the one of the park.

Let the circumference be (C) feet.

<eginalignC&=pi d\C&=dfrac227 imes 21\C&=66; extfeetendalign>

So,Michael will require a rope of length of 66 feet.
Example 2

John is repairing a pipeline in his bathroom.

The diameter that the pipe is 2 inches.


Can you identify the size of the tape to wrap approximately the pipe?


The diameter the the pipeline is (d=2 ; extinches).

To uncover thelength of the tape, we will identify the circumference of the pipe.

Let the circumference be (C) inches.

<eginalignC&=pi d\C&=dfrac227 imes 2\C&=6.285; extinchesendalign>

So, the compelled length that the tape is 6.285 inches.


Think Tank
1.A pizza of diameter (12; extinches) is sectioned into two equal semicircular parts.


Can you calculate the circumference of each part?

Interactive Questions

Here are a few activities for you come practice.

Select/Type her answer and click the "Check Answer" switch to see the result.

Let's Summarize

We expect you delighted in learning about Circumference come Diameter v the examples and practice questions. Now, you will be able to easily solve problems onthe Circumference to Diameter.

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Frequently asked Questions(FAQs)

1.What is the one of a 12-foot diameter circle?

The one of a circle v diameter 12 feet is calculation as:

<eginalignC&=pi d\C&=dfrac227 imes 12\C&=37.714; extfeetendalign>

2.Is diameter fifty percent of a circle?

No, the diameter is not half of a circle. That is double the radius that a circle.

3.What is the circumference of a 3-foot diameter circle?

The one of a circle with diameter 3feet is calculation as:

<eginalignC&=pi d\C&=dfrac227 imes 3\C&=9.428; extfeetendalign>

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