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

A circle has diameter = 9

Calculate Area, Circumference, Radius, Diameter

Calculate radius (r):

d = 2r

Rearranging the equation, we get:

r  =  d
  2

r  =  9
  2

r = 4.5

Calculate circumference (C):

C = 2πr

C = 2π * 4.5

C = or 28.2743

Calculate Area (A):

A = πr2

A = π * 4.52

A = 20.25π or 63.6173

Final Answers

r = 4.5
C = or 28.2743
A = 20.25π or 63.6173





What is the Answer?
r = 4.5
C = or 28.2743
A = 20.25π or 63.6173
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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