You can find the rate of change by taking it's derivative.
<h2>As a decimal: 20.56667</h2><h2>As fractions:
OR
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Are you trying to graph it because it is in y=mx+b form.
The circumference of a circle is equal to the diameter times pi. So, let's look at what happens if you double the radius of a circle -- say from 2 to 4. The area will go from 12.56 to 50.24. This means that it has quadrupled.
