4'2 Circumference of a Circle

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4.2 Circumference of a Circle
Circumference the distance around the outside
of a circle
This is the same as perimeter for other figures
The circumference of any circle divided by its
diameter is always equal to a number that is just
larger than 3.
This number is called pi (symbol is p) and is
equal to 3.141592653589. (it never ends or
repeats). We normally round this number to 3.14
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Circumference Calculations
Key Points c pd, or c p x 2r (c 2pr is
the same)
What is the circumference?
C pd C 3.14 x 8 cm C 25.12 cm The
circumference is 25.12 cm
8 cm
What is the circumference?
6 cm
C 2 p r C 2 x 3.14 x 6 cm C 37.68 cm The
circumference is 37.68 cm