The perimeter of a rectangle having area equal to 144 cm 2 and sides in the ratio 4 : 9 is

Let l = 4k and b = 9k
Area of rectangle = l x b
144 = 4k x 9k
⇒ k² = 144/36
⇒ k² = 4
∴ k = 2
∴ l = 8 cm and b = 18 cm
Perimeter of rectangle = 2(l + b)
= 2(8 + 18)
= 2 x 26
= 52 cm