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General Information, Facts & Tables
[Circle Calculator]

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Overview

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Image od circle showing names of dimensions. (Area in white)A circle is a two dimensional closed region where each point on its circumference is equal in distance from the centre.
The equation for a circle is (x - x0)2 + (y - y0)2 = r2

See Also: Open Another, Using the Calculators
 

Formula

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Required

Known

r

d

c

A

r

-

 r = d / 2

 r = c / pi / 2

 r = ( A / pi )0.5

d

 d = r * 2

-

 d = c / pi

 d = ( A / pi )0.5 * 2

c

 c = r * 2 * pi

 c = pi * d

-

 c = ( A / pi )0.5 * 2 * pi

A

 A pi * r2

 A pi * ( d / 2 )2

 A pi * (( c / pi ) / 2 )2

-

 

Units

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r = Radius in linear units.
d = Diameter in linear units.
c = Circumference in linear units.
A = Area in square units.
 

Calculator

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Show all available units

r []:

   

d []:

 

c []:

 

A []:

 

Note! Set unit values prior to calculating.