Answer: 9 feet.
Step-by-step explanation:
Given: A farmer needs to enclose a section of land in the shape of a parallelogram by using one side of a barn for one side.
We know that in<em> the opposite sides of parallelogram are equal.</em>
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Since, it is given that the barn and the side opposite of the barn will both be 13 feet long and one of the other sides will be 9 feet long.
Therefore, the last side must be opposite to 9 feet long side.
Hence, the length of the last side must be 9 feet.
