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Why is the area of a circle π•r•r?

Check out this video that explains why the formula for the area of a circle is π • r • r

Step 1: Cut circle into 1/8's

Step 2: Cut circle into wedges

Step 3: Rearrange the wedges to form a parallelogram.

Step 4: Notice the dimensions of this parallelogram.

Step 5: Radius is "r" and half the circumference is π•r.

Step 6: The area of a parallelogram is length x width.

 

Area of a circle = π• r • r

 

 

 

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Duane Habecker, 03/14/2010, Created with GeoGebra

Download this applet by clicking here.

 

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