of a circle is
I want to calculate
Area
Circumference
Radius
Diameter
All
  

    Take the Quiz

A circle has circumference = 20

Calculate Area, Circumference, Radius, Diameter

Calculate radius (r):

C = 2πr

Rearranging the equation, we get:

r  =  C
  

r  =  20
  2 * 3.1415926535898

r  =  20
  6.2831853071796

r = 3.1830988618379

Calculate diameter (d):

d = 2r

d = 2 * 3.1830988618379

d = 6.3661977236758

Calculate Area (A):

A = πr2

A = π * 3.18309886183792

A = 10.1321π or 31.8309

Final Answers

r = 3.1830988618379
d = 6.3661977236758
A = 10.1321π or 31.8309



Keep Practicing
Common Core State Standards In This Lesson
7.G.B.4
What is the Answer?
r = 3.1830988618379
d = 6.3661977236758
A = 10.1321π or 31.8309
How does the Circles Calculator work?
Free Circles Calculator - Calculates and solves for Radius, Diameter, Circumference, and Area of a Circle.
This calculator has 1 input.

What 3 formulas are used for the Circles Calculator?

d=2r
A = 2πr2
C=2πr

For more math formulas, check out our Formula Dossier

What 7 concepts are covered in the Circles Calculator?

area
Number of square units covering the shape
circle
the set of all points in the plane that are a fixed distance from a fixed point
circles
circumference
the perimeter of a circle or ellips
diameter
distance from two endpoints of a circle through the center
d = 2r
origin
On a two digit coordinate plane, the point (0, 0), where the x-axis and y-axis cross.
radius
Distance from the center of a circle to the edge
C/2π
Example calculations for the Circles Calculator
Circles Calculator Video

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