How to Find the Area and Circumference of Circles? (+FREE Worksheet!)
How to find the area and circumference of circles, step by step: the rule in plain language, solved examples worked one line at a time, and practice questions so you can try it yourself before moving on.
Learn how how to find the Area and Circumference of Circles when you have the radius or the diameter of the circle.
Parts of a Circle: what to notice and how to work it
What to notice first
Common student mistake
Key formulas and cues
A reliable path
- Label the diagramWrite each given measurement on the figure.
- Choose the formulaMatch the formula to distance, midpoint, area, volume, or angle relationships.
- Check unitsUse linear, square, or cubic units as appropriate.
Worked examples
Rectangle area
- Area of a rectangle is length times width.
- Substitute 8 and 3.
- Use square units.
Midpoint
- Average the x-values.
- Average the y-values.
- Write the ordered pair.
Try one before moving on
Parts of a Circle: pop-up practice
Watch this practice video for additional examples and reinforcement:
Related Topics
- How to Find Arc Length and Sector Area
- How to Find Equation of a Circle
- How to Find the Center and the Radius of Circles
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A step-by-step guide to solving Circles
- In a circle, variable (r) is usually used for the radius and (d) for the diameter, and (π) is about (3.14).
- Area of a circle (color{blue}{=πr^2})
- Circumference of a circle (color{blue}{=2πr})
Circles, Example 1:
Find the area of the circle. 
For education statistics and research
Use area formula: Area (=πr^2),
(r=6) (text{ in }), then: Area (=π(6)^2=36π)
(π=3.14), then: Area (=36×3.14=113.04) (text{ in }^2)
Circles, Example 2:
Find the Circumference of the circle. 
Solution:
Use Circumference formula: Circumference (=2πr )
(r=9 ) (text{ cm }), then: Circumference (=2π(9)=18π )
(π=3.14), then: Circumference (=18×3.14=56.52) (text{ cm })
Circles, Example 3:
Find the area of the circle. 
Solution:
Use area formula: Area (=πr^2),
(r=4) (text{ in }), then: Area (=π(4)^2=16π)
(π=3.14), then: Area (=16×3.14=50.24) (text{ in }^2)
Circles, Example 4:
Find the Circumference of the circle. 
Solution:
Use Circumference formula: Circumference (=2πr )
(r=6 ) (text{ cm }), then: Circumference (=2π(6)=12π )
(π=3.14), then: Circumference (=12×3.14=37.68) (text{ cm })
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Exercises for Solving Circles
Find the area and circumference of each circle. ((pi=3.14))
Download Circles Worksheet
- (color{blue}{text{ Area }: 50.24 text{ in }^2, text{ Circumference }: 25.12 text{ in }})
- (color{blue}{text{ Area }: 1,017.36 text{ cm }^2, text{ Circumference }: 113.04 text{ cm }})
- (color{blue}{text{ Area }: 78.5 m^2, text{ Circumference }: 31.4 m})
- (color{blue}{text{ Area }: 379.94 text{ cm }^2, text{ Circumference }: 69.08 text{ cm }})
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