The circumference of a circle is the distance around the circle. It is another name for the perimeter of a circle.
The circumference of a circle is calculated using the formula:
For any circle:
This number is Pi. It is a number which goes on forever.
The pi symbol ( ) allows you to give the exact value to a calculation involving circles as pi cannot be written as an exact fraction or decimal. If a decimal answer is required, the value can be approximated as 3.14 (3 significant figures).
Scientific calculators have a button which can be used during calculations, with the final answer being rounded off as appropriate.
Calculate the circumference of the dartboard.
The diameter is twice the radius.
Circumference = (1 decimal place).
The answer can also be given in terms of . In this case the answer is .
The circumference formula can be used to solve problems.
How many full rotations will the wheel make if it travels 3,500 cm?
Circumference of the wheel is: (1 decimal place)
In one rotation the wheel travels 172.8 cm (or 55 ).
To calculate the number of rotations:
This is 20 full rotations.