Express the area A of a circle as a function of its circumference C

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We know that the area of the circle is given as the following function:

A = (r^2)*pi where r is the radius.

But we know that:

C = 2r ( c is the circumference)

==> r = C/2

Now substitute with r = C/2

==> A = (c/2)^2 *pi

=...

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We know that the area of the circle is given as the following function:

A = (r^2)*pi where r is the radius.

But we know that:

C = 2r ( c is the circumference)

==> r = C/2

Now substitute with r = C/2

==> A = (c/2)^2 *pi

= C^2 / 4)*pi

= (C^2)*pi /4

A = (c^2)*pi/4

Approved by eNotes Editorial Team

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