The area of a rhombus is 216 square cm. One of the diagonal is 18 cm. What is the perimeter (in cm) of the rhombus?
Show answer & explanation
Correct answer: C
Explanation
Area = 1/2 × d₁ × d₂
216 = 1/2 × 18 × d₂
d₂ = 24 cm
Half-diagonals = 9 cm and 12 cm
Side = √(9² + 12²)
= √225 = 15 cm
Perimeter = 4 × 15 = 60 cm