of a circle is
I want to calculate

A circle has diameter = 19

d = 2r

##### Rearranging the equation, we get:

 r  = d 2

 r  = 19 2

r = 9.5

##### Calculate circumference (C):

C = 2πr

C = 2π * 9.5

C = 19π or 59.6903

##### Calculate Area (A):

A = πr2

A = π * 9.52

A = 90.25π or 283.5287

r = 9.5
C = 19π or 59.6903
A = 90.25π or 283.5287

r = 9.5
C = 19π or 59.6903
A = 90.25π or 283.5287
##### 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.
Distance from the center of a circle to the edge
C/2π