One of the four angles of a rhombus is 60°. If the length of each side of the rhombus is 8 cm, then the length of the longer diagonal is

Answer: Option A

Let ∠ABC = 60°
∠OBC = 30°
∴ Diagonals of Rhombus are the angle bisectors
In right ΔBOC
$$\begin{array}{rl}& \frac{\text{OB}}{\text{BC}}=\cos 30^{\circ }\\ & \frac{\text{OB}}{8}=\frac{\sqrt{3}}{2}\end{array}$$
OB = $$4\sqrt{3}$$
∴ BD = 2 × OB
= 2 × $$4\sqrt{3}$$
= $$8\sqrt{3}$$  cm