Circumference and Area of a Circle

To calculate the circumference (which is like perimeter) and the area of a circle, you need a special irrational number: pi. Pi is the ratio of the circumference of a circle to its diameter. Watch this lecture series to explore the circumference and area of circles, and complete the interactive exercises.

Practice

Area of a circle - Questions

1. Find the area of a circle with a circumference of 31.4 units.

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2. What is the area of the following circle?

Either enter an exact answer in terms of \pi or use 3.14 for \pi and enter your answer as a decimal.



_________ units ^{2}

3. What is the area of the following circle?

Either enter an exact answer in terms of \pi or use 3.14 for \pi and enter your answer as a decimal.



_________ units ^{2}

4. Find the area of a circle with a circumference of 6.28 units.

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5. Find the area of a circle with a radius of 2.

Either enter an exact answer in terms of \pi or use 3.14 for \pi and enter your answer as a decimal.

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6. Find the area of a circle with a diameter of 4.



Either enter an exact answer in terms of \pi or use 3.14 for \pi and enter your answer as a decimal.

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7.  Find the area of a circle with a circumference of 18.84 units.

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