The sides of a triangle are in the ratio 7 : 5 : 3 and its perimeter is 30 cm. Find the lengths of sides.

Since the sides of triangle are in the ratio 7 : 5 : 3, let the sides be 7x, 5x and 3x. Perimeter = Sum of sides of triangle ∴ 7x + 5x + 3x = 30 15x = 30 x = x = 2 ∴ x = 2, 7x = 14, 5x = 10, 3x = 6. Hence, the sides of the triangle are 14cm, 10cm, 6cm.