deriving the area and circumference of a circle

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• Apr 1st 2009, 04:12 PM
manyarrows
deriving the area and circumference of a circle
Could anyone show me the proof for circle area and circumference. I saw a animated argument that give me the basic theory on circle area but it went to fast to get a firm understanding.
• Apr 3rd 2009, 04:07 PM
stapel
Quote:

Originally Posted by manyarrows
Could anyone show me the proof for circle area and circumference. I saw a animated argument that give me the basic theory on circle area but it went to fast to get a firm understanding.

What, precisely, are you seeking to have proved? What formula or relationship?

What theorems, formulas, etc, are you allowed to use in your proof?

Thank you! :D
• Apr 3rd 2009, 06:38 PM
manyarrows
further explaination
I have actually found the argument for the area of the circle. The one where you cut it up into tiny pieces and reassemble it as a square and then use the area of the rectangle $r\pi\times r$.

My question now is how do we come up with the circumference of the circle. I'm not looking for a formal proof neccessarily, just a practical explanation.
• Apr 3rd 2009, 07:15 PM
mr fantastic
Quote:

Originally Posted by manyarrows
Could anyone show me the proof for circle area and circumference. I saw a animated argument that give me the basic theory on circle area but it went to fast to get a firm understanding.

Read this: http://www.fiu.edu/~rudomine/pi.pdf