For a given perimeter, the rectangle with the largest area is a square. For a given area, the rectangle with the smallest perimeter is a square. What do the above sentences mean? Can any one explain the concepts with examples?
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Think about the inequality $ab \leq \left( \frac{a+b}{2} \right)^2$. – GAVD Sep 03 '15 at 07:28
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2For a given area the rectangle with the smallest perimeter is a square. – Mark Bennet Sep 03 '15 at 07:35
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Suppose the perimeter is $24$.
The rectangle could be $1\times 11$ with area $11$ or $4\times 8$ with area $32$ but the greatest area is $6\times 6=36$.
Suppose the area is $36$.
The perimeter could be $74$ with sides $36\times 1$ or $30$ with sides $3\times 12$. But the smallest perimeter would be $24$ for a square of side $6$.
Mark Bennet
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