Area, Perimeter and Measurement for Dummies

Regular polygons

If you've ever read a Grisham novel or watched a courtroom drama, you probably have the mistaken impression that the lawyer is always the smartest guy in the room (if you'd prefer to be disabused of this notion immediately, you need only read a Lisa Scottoline novel). In reality, however, the average lawyer isn't any smarter than anybody else. Or even as smart as many... Our Antisocial Network staffers know this because first, several have sat on juries and watched real lawyers in action and second, because they've seen eHow.com's Carter McBride, JD, in action, when he posted rubbish like "How to Calculate Acreage From Perimeter," which Leaf Group has moved to Sciencing.com.

Although McBride claims to have both a JD and a MS (it's in Accounting: is there really such a thing?), he apparently didn't take much math; especially geometry. Had he done so, he might have used his words more carefully in the introduction to the post:

"Of common shapes, only a rectangle 's [sic] area is calculable by measurements of only the perimeter..."

...which, as we here at the Antisocial Network can attest, is utter bullshit. You cannot directly calculate a polygon's area from its perimeter for any shape unless it is a regular polygon (all sides are equal) and you know both perimeter and number of sides; plus some higher math. With that information, you can learn the approximate area of any regular polygon from its perimeter (given some work...) Since Carter's stuck on a quadrilateral, let's choose the regular, four-sided polygon, i.e., the square. If the perimeter of a square is 600 feet, each side is 150 feet long, which means its area is 22,500 ft² – about 0.516 acres. Kudos, by the way, to Carter for managing to find the number of square feet in an acre, 43,560 (said kudos is, we suspect, actually due Google). If you're reasonably competent at math and have enough time on your hands, you can calculate the area of a regular polygon with those two pieces of information. McBride, however, is confused: he thinks that you can calculate the area of a rectangle from its perimeter, but his method is to

1. Measure a side
2. Measure a non-parallel side
3. Multiply the two numbers

That procedure, when you get right down to it, isn't calculating the area from the perimeter, it's calculating area from a pair of measurements. But hey: who are we to argue with a JD? after all, they're the smartest people in the room; NOT. In fact, this one's not that smart at all: this entry marks the third time Carter McBride. JD, has been our Dumbass of the Day.

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