# Method of calculating the circumference

## Contents

• 1 circuit definition
• 2 How to calculate the circumference of a circle
• 3 How to find the perimeter manually circle
• 4 important concepts related to the department
• 5 examples illustrate how to calculate the circumference of a circle
• 6 video about the circle with an area and its environs
• 7 References

## Definition of the circle

Circle (in English: Circle): is a closed geometric shapes consisting of a set of points that connect with each other closed curved line; Since each of these points away from a fixed dimension to a specific point located inside the circle called the center. [1] [2]

## How to calculate the circumference of a circle

If they were to bring three different circles of space, and asked to find the ratio between the length of circumference to its diameter, it is simply a circumference of a circle by using the method that has been mentioned previously, and then divided by the length of the diameter; As recorded as a result of each circle separately, you will notice after the codification of outputs that the ratio between the circumference of a circle to a constant among all circles in diameter no matter how different area, hence the ratio between the circumference of a circle to its diameter does not change (fixed) are approximate ratio; Where approximately equal to 7/22 or 3.14, and denoted by the symbol (π), eBay and read. As for the circumference of a circle, it is a curved line that limits the length of the circuit, and to calculate the perimeter of the circle algebraically law the following uses: circumference = 2 × π × Purify or circumference of a circle = π × s. [3]

## How to find the circumference manually

It is known that the circuit is different from other geometric shapes being devoid of straight lines, and is composed as a result of the delivery of a set of points a curved line, and to find the perimeter of circular shape tray using the thread, there is a set of steps that must be followed, which is as follows: [3]

• The first step: to fetch a string or standard tape length appropriate; Which proves the tip on the edge of the box using the sticker.
• Step Two: The briefing the other end of the string around the circular enclosure so that completes a full cycle without an increase or decrease.
• Step Three: Place the string is determined that the session has been completed and cut using scissors.
• Step Four: to loose the thread of the body that was installed, and then measured by the length of one of the appropriate measurement tools (ruler or tape record), then the length of the string will be measured exactly equal to the length of the curved line that surrounds the box, which represents the circumference of a circle.

## Important concepts related to the department

There is a set of concepts related to circular in shape, and these concepts include: [4] [5]

• (Center of the circle and symbolized by the symbol m): It is a point located in the middle of the circle completely; So that the distance between them and any point on the edges of the circle is a fixed distance.
• (Diameter of the circle and denoted by s): the length of the piece that link between any two points on the circle Tqaan; Provided that the passage of this piece Circle Center.
• (Radius of the circle and Armzlh symbol Purify): the length of the piece that link between the center and any point on the circle.
• (Chord) is a straight piece which is located Janebaha on the borders of the circle, and if it happened that this piece went through the circle center, then be called in diameter.
• (Cutter) is the straight line which cuts the circle with two points located on the borders of the circle.

## Examples show how to calculate the circumference of a circle

• Example 1: Calculate the perimeter of a circular room if aware that the radius of 19:00.
• Example 2: Calculate the circumference of a circle if you know that the diameter is equal to 100 mm.
• Example 3: Can a circular shape along the radius of 0.5 creamy, very surroundings. [6]
• Example 4: circular garden shape along the diameter of 98 m, the owner wanted a fence enclosed in a metal, how the cost of the fence if I learned that the price of a meter per four and a half dinars. [7]
• Example 5: Square circular shape, if I learned that the circumference is equal to 66 m, the length of very diameter. [3]
• Example 6: circular swimming pool with a radius equal to 3.75 m, calculate the distance made by Ali if he ran around the swimming pool 8 full sessions. [3]

## References

• ↑ "Set of All Points That", www.mathsisfun.com, Retrieved 13-1-2018. Edited.
• ↑ "Circle", www.mathsisfun.com, Retrieved 13-1-2018. Edited.
• ^ A b t w Fadwa Junkie, Secretary Almstrhristi, Mohammed Arabiyat (2007), Mathematics Teacher's Guide sixth grade (first edition), Jordan-Amman: Ministry of Education Curriculum Management and textbooks, the third unit 91-122 page 94-98 Measurement File Answers questions 273-305 p. 292, Part I. Adapted.
• ↑ " Circles", www.math2.org, Retrieved 9-11-2017. Edited.
• ↑ " Definitions of Parts of Circles", www.algebralab.org, Retrieved 3-11-2017. Edited.
• ↑ "Circle", www.mathsisfun.com, Retrieved 3-11-2017. Edited.
• ↑ Educational Supervisor (2016), answers engineering unit - part 2 seventh grade core (first edition), Jordan-Amman: Administration curricula and textbooks, page 6-7-8, the second part. Adapted.

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