If the area of a rhombus is 54 sq.cm and the length of one of the diagonals is 6 cm then the length of the other diagonal is -

A 18 cm

B 12 cm

C 9 cm

D 6 cm

Correct Answer: Option A

Area of rhombus = \({1 \over 2} \times {d_1} \times {d_2}\)

Where d₁ and d₂ are the diagonals of the rhombus,

\(\eqalign{ & \Rightarrow 54\ {cm^2} = {1 \over 2}{d_1} \times {d_2} \cr & \Rightarrow {d_2} = 18\ cm \cr}\)

Hence, length of the second diagonal would be 18 cm.