# Is Bob's method for determining the area of the irregular shape valid or not?

Bob wants to find the area of an irregular shape. He cuts a piece 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 the centimeter graph paper. Using the graph paper, he determines that the area of his string square is about 225 cm^2. Bob says that the area of the irregular shape os therefore also 225 cm^2. Is Bob's method for determining the area of the irregular shape valid or not? IF the method is not valid, what can you determine about the area of the irregular shape from the information that Bob has?

By:

Tutor
5.0 (243)

Mathematics Teacher - NCLB Highly Qualified

David W.

tutor
From the information that Bob has [ C=60 ], we can determine that the area of the irregular shape is less than 286.5 cm2 because the area if a circle [ A=C2/(4π) ] is the maximum for a given perimeter.
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04/09/16

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