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If a circle and a square have the same perimeter, their areas will be different.

Pi times r-squared means Pi x radius x radius. It does NOT mean Pi x radius x 2.

**Study and practice**

- Try your hand at changing the area enclosed by a circleThis page on mathopenref.com lets you see how the area of the circle changes as you adjust its radius.
- Quiz yourself on finding the area of circlesThis quiz at aaastudy.com will help you check your understanding of the circle area calculation.

Use these search terms to find additional resources:

*how to find the area of a circlecircle area*