Area of a REGULAR Polygon

8 Apr

The area chapter is so much fun! This is the chapter where I can easily say, it’s not about the formula, but coming up with the formulas. It’s not about the answer, but explaining how you found your answer. Making connections is easy to incorporate and there’s just so many activities that can be done!

To start my posts for this chapter, an activity that I love. This worksheet is to discover the area formula for a regular polygon. I really did not want to introduce yet another formula when this one is so easy to just split into triangles. However, I also wanted them to know the formula the book uses because I remember last year a bunch of students thinking the ‘a’ in (1/2)ap representing area (of what? I have no idea and neither did they.)

Sequence: After covering the area of parallelograms, triangles, rhombuses, kites, trapezoids. I had been mainly focusing on coming up w/ the formulas for a rhombus, kite, and trapezoid using the area formulas for parallelograms, triangles, and rectangles only.

Time of activity: 30 minutes?

Introduce: Vocab words, “apothem” and “radius” of a regular polygon. (Review “regular”).

Execution: Partner work.

A snippet of what the activity looked like:

Screen Shot 2013-04-08 at 8.21.37 PM

It goes on for a few more questions, but my favorite part that I added is this one:

Screen Shot 2013-04-08 at 8.22.04 PMThey did a pretty swell job of figuring out why, I just had to help them a bit in actually getting it into writing.

Full activity here, on my very baby-bud of a Geometry site.

Note (to self): ADD problem w/ connection of A=(1/2)ap to the area of a circle!

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