|
|
|
|
|
Circumference of a CircleFormula for circumference with examples The circumference of a circle is the edge or rim of a circle itself. It is the equivalent of 'perimeter' for a circle. In other words, if you took a circle and unrolled it, you would have its circumference. You can use either of the formulas below to find circumference of a circle. One formula use the radius of a circle; the other formula uses the diameter.
This Page: Practice Problems | circumference formula Related Pages: Standard Form Equation for a Circle | Chord of Circle| Tangent to a Circle |Arc | Inscribed Angles
The rotating line on the left is an example of a circle's radius.
If the radius of a circle is 1 inch (1"), then the circumference of the circle = 2Π• 1" ≈ 6.28"
Practice Problems
Problem 1) What is the circumference of the circle below. 
Circumference Circumference = 2Π• radius  = 2Π• 15 = (30• Π)"
≈ 94"
Problem 2) What is the circle's circumference?
Circumference
Circumference = 2Π• radius 2Π•9 = (18×Π)"≈ 56.5"
Problem 3) What is the circumference of the circle pictured below?
Circumference
Circumference = 2Π• radius 2Π• 71" = (142Π)" ≈ 446"
Problem 4) What is the circumference of a circle with a radius of 5"?
Circumference Circumference = 2Π• radius 2Π• 5 " = (10Π)"
≈ 31.4"
Practice Problems (Medium)
Problem 5) A circle's circumference is (22Π)". What is the radius of this circle? radius circumference =2Π•r = 22Π" r = (22Π")/2Π = 11"
Problem 6) A circle's circumference is (102Π)". What is the diameter of the circle?
diameter circumference = 2Π•r = d×Π= 102 Π" d = (102Π")/Π = 102" Top |
