The perimeter of a rectangle is 72 cm. If the ratio of the lengths of two adjacent sides is 7 : 5, find the lengths of these sides.

Question: The perimeter of a rectangle is 72 cm. If the ratio of the lengths of two adjacent sides is 7 : 5, find the lengths of these sides.

Solution:
Perimeter of a rectangle = 2(Length + Breadth)
Also Length : Breadth = 7 : 5
Let actual values are 7x and 5x.

Hence,
2(7x + 5x) = 72
⇒ 12x = 36
∴ x = 3

Now,
Length = 7x = 7 × 3 = 21 cm
Breadth = 5x = 5 × 3 = 15 cm

∴ sides will be of 21 cm and 15 cm.