Question

a rectangular area of 18 cm if its length and with whole number what is the greatest possible of perimeter

Answer 1

Answer:

Let's say its length is X cm

Therefore it's width is (18/X) cm

Perimeter is 2×(L + B)

= 2×(X + 18/X)

P = 2X + 36/X

(dP/dX) = 2 - 36/X^2 = 0

Which gives X = ✓18 but this is not a whole number. X = 4.242

So we take the nearest number for which both X and 18/X are whole numbers

Which is 3

Hence Length is 6 cm, Breadth is 3 cm and Perimeter is 18cm