Chapter 12.8, Problem 11P

Bob wants to find the area of an irregular shape. He cuts a plece of string to the length of the perimeter of the shape. He measures to see that the string is about 60 cm long. Bob then forms his string into a square on top of centimeter graph paper. Using the graph paper, he determines that the area of his string square is about 225 $c{m}^2$ . Bob says that the area ofthe irregular shape is therefore also 225 $c{m}^2$ . Is Bob’s method for determining the area ofthe irregular shape valid or not? Explain. lfthe method is not valid, what can you determine about the area of the irregular shape from the information that Bob has? Explain.