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Circle Perimeter Formula

The circumference

of a circle

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or

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The circumference

of a circle

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First we need (pi)

Is it…..3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679821480865132823066470938446095505822172535…..?

What is ?Is it a number?

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Well… not exactly.

is a ratio.

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Pi is the number of times you must travel straight across the circle to go the same distance as all the way round the circle.

Once acrosstwice across

So is a bit more than 3.Click the mouse

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three times acrossand a bit further!

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How can we be sure that is a bit more than 3?

For a regular hexagon, the distance all the way round is exactly 3 times the distance straight across the middle.

123

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And all the way round the circle is a little bit more than all the way round the hexagon.So all the way round the circle is a little bit more than 3 times straight across the middle.

Circumference = × DiameterClick the mouse

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Summary

Circumference= × Diameter