Ellipse Area for the Dummy Geometry Student

Area of ellipse calculation inputs

It's pretty common for our staffers to refer to what we call the "stupidification of the internet," usually at the hands of an un- or at least under-educated freelancer. The proliferation of fake news and moronic memes notwithstanding, we'd like to think that the dumbassery we point out on these pages helps reduce the bogosity somewhat, but it seems hopeless. It seems hopeless, at least this time, because the mother lode of misinformation seems hellbent on making things worse. Witness freelancer Jon Zamboni and his rewrite of the post, "How to Calculate the Area of an Oval" at Sciencing.com.

At some point in 2016, Demand Media (now known as Leaf Group) paid "Zamboni" to rewrite that particular title. We don't know why, because the original¹ (by Chris Shore) was actually correct. Zamboni, compliments of a religious studies degree, made a mess of it (he's blown geometry rewrites before). We won't get into the fact that "oval" is a non-specific term, or that ovals and ellipses are not the same thing. Let's just pretend, for now, that Zamboni was asked for how to calculate the area of an ellipse.

If you think about it for a moment, a circle is just a special case of a circle. We're not kidding: the area of an ellipse is the product of π, the semi-major axis (a), and the semi-minor axis (b): A = π * a * b In a circle, the semi-major and semi-minor axes are equal, and both are the radius r. In other words, A = π * r * r  or A = π * r² Well, Zamboni tried to get there: he went into long and involved discussions of the dimensions of an ellipse (again, we're ignoring the difference between an ellipse and an oval) before intoning that,

"Calculate the area as pi * major axis * minor axis. "

To that, he added an example:

"For example, an ellipse has a major axis of 10 inches and a minor axis of 6 inches. The area is 3.14 * 10 * 6 or 188.4 square inches."

Umm, no, Jon, you multiply π times half the major axis times half the minor axis.² If your ellipse were a circle, you'd have told people that the area is π times the diameter squared, or four times the actual area. The actual area of your example ellipse is 3.14 * 5 * 3, or 47.1 – and yes, 188.4 ÷ 4 equals 47.1... idiot.

Congratulations, Mr. Zamboni, for you are now the proud owner of two Dumbass of the Day awards!

¹ You can see Shore's version (which also confuses "ellipse" and "oval") using the Wayback machine at archive.org. Check out the URL    ehow.com/how_4760748_calculate-area-oval.html
² We note with amusement that, more than two years after this publication, the powers that be at eHow... errr, Leaf Group... corrected the egregious error made by Mr "Zamboni." Just so's you know we weren't full of hooey when we caught the error in 2018, have a look at the original using the Wayback Machine at archive.org and the URL   sciencing.com/calculate-area-oval-4760748.html.

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