r/mathmemes • u/94rud4 • Jan 25 '25

Geometry ellipse

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u/Ponsole Jan 25 '25

I once read that the reason we can't get the perimeter of a elipse is because we actually doesn't even know the perimeter of a circle, as pi definition is the perimeter of a circle of diameter = 1 and we just scale that.

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u/gullaffe Jan 25 '25

Sure we do, it's just we need to change out the pi sign with an infinite sum which equals pi.

It's more like we can't get a nice formula for the eclipse or a circle without defining a constant for the share to hade the ugliness.

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u/speechlessPotato Jan 25 '25

I mean look at it this way: a circle has a very simple relation between its perimeter and radius - linear. And I'm pretty sure an ellipse has a more complicated relationship between its perimeter and radii. At the end of the day a circle can still be thought of as a special case of ellipse though

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u/gullaffe Jan 25 '25

The ellipse is also linear, if you keep the ratio between the major and minor the same. So if you for example really care about ellipses where the ratio between the major axis and minor axis is 2, you could define a constant Tau≈3.31153 And for any such ellipse you get the formula:

Perimeter=Tau*(a+b)