How Area Changes with Diameter

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It is easy to believe that when you change one dimension of a figure, its area changes by the same percentage. However, this is incorrect.


The area of a circle changes with the square of its diameter. For example, doubling the diameter quadruples the area. Another example: tripling the diameter makes the area go up by a factor of nine.


Contributed by: Sarah Lichtblau (March 2011)
Open content licensed under CC BY-NC-SA




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