Page 43 - ArithBook5thEd ~ BCC

9

8

7

6

5

4

3

2

1

0
0 1 2 3 4 5 6 7 8

Solution. Using the grid, it is easy to find the lengths of all six sides of the polygon. For example, the
left-hand vertical side is 7 cm long (stretching from 1 to 8 on the scale at left), and the top side is 2
cm long. Continuing clockwise around the L-shape, we see that the side lengths are

7, 2, 5, 4, 2, 6 cm,

respectively. From this, it follows easily that the perimeter P is given by the sum

7+ 2 + 5+ 4 + 2 + 6 = 26 cm.

To find the area, we draw a line which divides the L-shape into two rectangles (labeled R 1 and R 2 )in
the figure below. (We could have drawn a different line to obtain a different division into two rectangles
–do you see it?)

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