How to Find the Area of a Circle
The area of a circle is π times the square of the radius.
Radius vs diameter
If you are given a diameter d, the radius is d/2. Do not plug the diameter into πr².
Step-by-step method
- Find r.
- Square it.
- Multiply by π.
Example
radius 5
- 25π
Answer: 25π
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Example problems
Common mistakes
Using 2πr for area
2πr is circumference, not area.
Related formulas
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Frequently asked questions
What units?
Square units: cm², in², and so on.