A circle has diameter = 4

Calculate Area, Circumference, Radius, Diameter

Calculate radius (r):

d = 2r

Rearranging the equation, we get:

r  =  d
  2

r  =  4
  2

r = 2

Calculate circumference (C):

C = 2πr

C = 2π * 2

C = or 12.5664

Calculate Area (A):

A = πr2

A = π * 22

A = or 12.5664

Final Answers


r = 2
C = or 12.5664
A = or 12.5664


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Common Core State Standards In This Lesson
7.G.B.4
What is the Answer?
r = 2
C = or 12.5664
A = or 12.5664
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
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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