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PLSO Issue 2 2015 March April

Become a Certified Survey Technician 13 Professional Land Surveyors of Oregon | www.plso.org PLSO puzzler „ John Thatcher, PLS This is a really good thought experiment that I stole from the Car Talk Puzzler Department. Well, they are always stealing stuff, so touché. I’ve changed the needle to protect the record. You have just hired a greenhorn off the street to work on your field crew. Your client, an asphalt contractor, wants you to measure a perfectly circular go-cart track and tell him the area of the track so he can order the correct amount of asphalt. The track (tract?) in question looks like a donut in plan view—it has two concentric circles, an inner circle and an outer circle. The track, of course, is the area between the two circles. “I wish all jobs were this easy,” you say. You don’t even need a total station, GPS, digital level, scanner, drone, AutoCAD, MicroStation, Carlson—anything but a tape measure. So you tell your greenhorn (she is your engineer’s daughter, so she isn’t really off the street) to take a tape measure out and simply measure the two radii. The new hire goes out to the project and comes back to say that she couldn’t measure the radii because there is too much equipment in the donut hole. But she did bring back one measurement: the length of the chord on the outer circle that is tangent to the inner circle. That length is 93.73 International Feet (must be in Oregon). The question is, is that enough information to compute the desired area, and if so, what is that area? Let’s pretend we’re back in school. The answer, if there is one, is not enough. Show your work. See the next issue for the answer. And no, my answer was not picked at random as more-or-less correct. ◉ ENHANCE YOUR CAREER OPPORTUNITIES INCREASE YOUR SKILLS www.learncst.com Set a Straight Course to Your Future PLSO PUZZLER


PLSO Issue 2 2015 March April
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