Area and circumference both relate to the radius and diameter of a circle. Once you know one, you can find all of the others --It just takes a little math!

Related Pages: standard form equation for a circle |arc|tangent | chord |

chord's perpendicular bisector |circumference | Intersection of chords

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Practice Exercises

If a circle's diameter is 10, calculate its circumference and area?

Answer

circumference = Π×diameter = 10 Π

radius = diameter÷2 = 10÷2 =5

area = Π(radius)² =Π(5)² = 25Π

If a circle's diameter is 10, calculate its circumference and area?

Answer

circumference = Π×diameter = 10 Π

radius = diameter÷2 = 10÷2 =5

area = Π(radius)² =Π(5)² = 25Π

A circle's area is 16Π. What is its circumference?

Answer

A = Π (radius)² = 16Π radius² = 16 radius = 4

circumference = 2Π×radius =2Π×4 = 8Π

Answer

A = Π (radius)² = 16Π radius² = 16 radius = 4

circumference = 2Π×radius =2Π×4 = 8Π

If a circle has a circumference of 26Π, what is its area?

Answer

circumference = 2Π(radius) = 26Π 2×radius = 26 radius = 13

area = Π(radius)² =Π(13)² =169Π

Answer

circumference = 2Π(radius) = 26Π 2×radius = 26 radius = 13

area = Π(radius)² =Π(13)² =169Π