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 Math Central Quandaries & Queries
 Subject: Length of ellipse Name: Tom Who are you: Other How do I determine the length of an ellipse if the width and area are known?

Tom,

The equation of Area of an Ellipse is

A = π a b

where a and b are half the lengths of the major and minor axis. If we think of a circle, it is just a special case of an ellipse where a = b, the radius of the circle. That is why we say A = π a2

Looking at the formula, we can say that a is half the length and b is half the width. We just have to now manipulate the formula to find 2a in terms of A and 2b.

Karen and Sue

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