Question

The perimeter of a rectangular window is 100 m.find its maximum area.​

Answer 1

→  Let the length and breadth of the rectangle be x and y

Perimeter of rectangle P=2(x+y)

100=2(x+y)

⇒x+y=50        ....(1)

→  Area A=xy

A=x(50−x)

For maximum or minimum,

$\frac{dA}{dx} =0$

$50-2x=0$

$x=25$

→  Thus, A is maximum at x=25

Hence, area is maximum at x=25,y=25 ■

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