Math Photo: Pyramid Projection

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Naturally, the geometry of this simple piece of playground equipment caught my eye, but the shadows really sparked my interest.

The shadows are the projections of the edges of this pyramid, and they form a set of angles on the ground.  Notice immediately that the largest angle (the shadow formed by the “back” face) is the sum of the other three angles.

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There are many other interesting questions to ask, and relationships to explore.  What I was most curious about, however, is how accurately we could locate the sun in the sky based only on this information.

 

Regents Recap — June 2014: Are They Reading?

Here is another installment in my series reviewing the NY State Regents exams in mathematics.

I have been reviewing New York State Math Regents exams for several years now, and I occasionally wonder if anyone involved in the production of the exams pays attention to what I say.

Well, last year I wrote about a problem on the Geometry exam that asked students to graph a compound locus but then incorrectly penalized them if they didn’t graph each individual locus.  The supervisor at the grading site didn’t take our complaints seriously, but It seems the exam authors eventually realized that this was wrong.

This is from the 2014 Geometry exam.

2014 Regents Geom -- locus

Notice how this question explicitly asks the student to graph both individual loci.

I doubt that my post instigated the change, but it is nice to see errors on these exams addressed every once in a while.

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