study hall conversation
So how can we speed
up the area calculation
for a parallelogram?
Jim: Well, a parallelogram is basically made up of just three
shapes, a rectangle and two triangles.
Frank: Yeah, but those two triangles look the same, right? So
maybe they’re congruent.…
Joe: Nice! So we could calculate one triangle area, multiply by
two, and then add on the area of the rectangle.
Jim: That’s still a few calculations per lawn, duh!
Frank: True. So I wonder if we could take it any further?
Joe: Maybe we can move these shapes around a bit. Could
we turn them into just one shape whose area we know how to
242 Chapter 6