Math and Arithmetic
Geometry

# What is the perimeter of a circle?

2 x pi x r where pi = 3.1416

To find the perimeter you do pi (3.1415) times the diameter.

Or you can figure by the radius (P=2 π r; i.e. Perimeter = 2 x

The perimeter of a circle is its circumference. We use these

formulas to find the circumference of a circle; C=d times pi or C=2

times the radius times pi (3.14).

To make it easier to explain:

Area: Pi (3.14) X Radius Squared (r 2) from the center out of

the circle

Perimeter: Pi (3.14) X Diameter (d) from one side of the circle

to the other

The perimeter of a circle is called Circumfrence.

Here is the formula for Circumfrence:

C= pi x d (pi times diameter)

C= 3.14 x ______ (fill in the blank with the diameter of the

circle)

NOTE: Pi is equal to 3.14 so when you are using pi to multiply,

replace it with 3.14

When the diameter is not given in a circle, double the radius to

find the length of the diameter.

The perimeter of a circle is its circumference

The perimeter of a circle is its circumference

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