The perimeter of a rectangle is 40 m. If the sides of the rectangle are natural numbers,
find the dimensions of the rectangle having the maximum area. please explain properly
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Answer:
Let l and b are the sides of rectangle.
∴2(l+b)=40
⇒l+b=20 …(1)
If the area of rectangle is A, then
A=l⋅b
l(20−l) [From eq. (1)]
=20l−l2
⇒dAdl=20−2l
For maxima/minima
dAdl=0
⇒20−2l=0
⇒l=10cm
And d2Adl2=−2<0
∴ At l=10cm, is maximum.
Therefore, for maximum area, the sides of rectangle are 10 cm and 10 cm.
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