Definition of OvalDate: 06/09/2002 at 20:15:44 From: Jeff McAffer Subject: definition of an "oval" We were recently given a book of geometrical shapes for our 7 month old daughter (never too early for math!). In the book there is a drawing of an ellipse with the label "oval". The next page has a real world example of a chicken's egg. We both agree that the egg is oval (I believe this is the origin of the word) but what of the ellipse? So I started searching your site (very nice!) and found http://mathforum.org/library/drmath/view/55368.html which clearly positions ellipses as ovals. Great. But the discussion raised questions as to the exact definition of "oval". The Exeter description says: "... This is distinct from an oval where the perimeter has only to be a concave curve, and there are many possibilities" By this wording, a circle is an oval. Something resembling a right angle triangle with rounded corners is an oval, ... Seems overly broad and quite contrary to popular conception. Is there a more exact/narrow definition of "oval"? Many thanks and keep up the good work. Jeff Date: 06/09/2002 at 23:10:26 From: Doctor Peterson Subject: Re: definition of an "oval" Hi, Jeff. The word "oval" merely means "egg-shaped"; you are right that it comes from the Latin word for "egg". It is not a precisely defined mathematical term. If we wanted to make it more precise, we might require these features: continuous, smooth closed curve convex ("concave" is a misprint on that site!) not an exact circle one axis of symmetry longer along the axis than across it An ellipse fits all but the single axis of symmetry; it is more symmetrical than many eggs. That requirement is not always included in defining "oval". But because there is no mathematical gain in defining this term, which covers a variety of figures anyway, there is no need to define it more precisely from our perspective. We just know an "egg" when we see it (and don't argue if someone else disagrees!). - Doctor Peterson, The Math Forum http://mathforum.org/dr.math/ |
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