The area of a rhombus is 216 square cm. One of the diagonal is 18 cm. What is the side (in cm) of the rhombus?
Show answer & explanation
Correct answer: A
Explanation
Area of the rhombus = 1/2 × d₁ × d₂
216 = 1/2 × 18 × d₂
d₂ = (216 × 2) / 18
= 24 cm
The diagonals of a rhombus bisect each other at right angles.
Halves of the diagonals:
18/2 = 9 cm and 24/2 = 12 cm
Side = √(9² + 12²)
= √(81 + 144)
= √225 = 15 cm