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 Question from Sherri, a teacher: I have a lot that is 2565 x 1056 x 2636 x 285 that is roughly in the shape of a triangle, with the small strip on the top of the triangle, that I would like to figure the sq. footage for.  Could I draw a line from one corner on the top to the opposite corner on the bottom and get the area of those two triangles, then add that together to come up with the sq. ft.?

Wonderful Sherri!

That's exactly the approach that will give you the accurate area of land.

The reason I'm so pleased is that many people ask us to determine the area of a four- or more-sided property with just the length measurements, not realizing that these alone don't provide a single shape (and therefore area). We have even written an F.A.Q. article on this with a demonstration of the problem.

Once you measure the diagonal's length, you can use Heron's formula to compute the area of each triangle, add them up and you'll have your total square footage (if you measure distances in feet, that is).

Then divide by 43560 square feet per acre to get the acreage.

Cheers,
Stephen La Rocque.

Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.