Content

• Steps
• Method 1 of 2: Through Diameter
• Method 2 of 2: Through the Radius
• Tips
• Warnings

Whether you're working on a project, doing handicrafts, or just wanting to know how many meters of fence you need to enclose your backyard jacuzzi, you need to calculate the circumference for all of this.

Steps

Method 1 of 2: Through Diameter

1. 1 Write down the formula for calculating the circumference in terms of the diameter. The formula is: C = πd, where C is the circumference, d is the diameter of the circle. That is, the circumference is equal to the product of the diameter by the number pi (π is approximately equal to 3.14).
2. 2 Plug the given values ​​into the formula and find the circumference.
   • Example: You have a round pool with a diameter of 8 m and you want to put a fence around it at a distance of 6 m. To calculate the length of the fence, first find the diameter of the circle, that is, the diameter of the pool plus the distance to the fence on both sides. In our example, the diameter is 8 + 6 + 6 = 20 m. Plug this value into the formula.
   • C = πd
   • C = π x 20
   • C = 62.8 m

Method 2 of 2: Through the Radius

1. 1 Write down the formula for calculating the circumference in terms of the radius. The radius is half the diameter, and the diameter, respectively, is two radii (2r). Then the formula looks like: C = 2πr, where C is the circumference, r is the radius of the circle. That is, the circumference is equal to twice the product of the radius and pi (π is approximately equal to 3.14).
2. 2 Plug the given values ​​into the formula and find the circumference. For example, you cut out strips of decorative paper to wrap nicely around cupcakes when serving. The radius of the cake is 5 cm. Plug this into the formula.
   • C = 2πr
   • C = 2π x 5
   • C = 10π
   • C = 31.4 cm.

Tips

• You can buy an engineering or scientific calculator that already has a π button. This way you have to press fewer buttons, and the answer will be more accurate, since the built-in π button has a more accurate value than 3.14.
• To calculate the circumference, knowing the diameter, simply multiply the diameter by pi.
• The radius is always half the diameter.
• When solving a problem, you may be required to write not the π symbol, but its numerical value - 3.14 (or with a large number of decimal places). Check with your teacher for requirements.

Warnings

• If you can't solve a problem, ask friends, family members, or a teacher for help. They will always help!
• Remember to double-check the calculations, as one mistake will lead to the wrong result.
• Do not hurry. Remember the old adage - measure seven times, cut once.