Circumference of a circle - 4th Sep 2008
Today’s lesson was about the circumference of a circle. We looked at how the circumference is the distance around the outside of the circle and discussed the connection between the diameter and circumference of a circle.
We discussed that Pi (∏), which is the number that connects the diameter and circumference is approximately 3. Sometimes you are required to use an accurate value for Pi on your calculator and sometimes you are asked to use an approximate value such as 3.14.
Calculating the circumference of a circle
To calculate the circumference of a circle we use the formula
Circumference = ∏ x Diameter
C = ∏D
(or C = 2∏r if you have the radius)
So for this circle the circumference is calculated by
C = ∏ x 6
C = 18.8 cm (1dp)
For more help or to see how the circumference and the diameter are connected see the Mymaths lesson.
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