We know that,

A rhombus is a simple quadrilateral whose four sides are of same length and diagonals are perpendicular bisector of each other.

The figure is:

Given: AC = 16 cm and BD = 12 cm

∠AOB = 90°

∵ AC and BD bisects each other

→ AO = � AC and BO = � BD

→ AO = 8 cm and BO = 6 cm

Now, in right angled ∆AOB,

As per by Pythagoras theorem,

→ AB � = AO � + OB �

→ AB � = 8 � + 6 � = 64 + 36 = 100

∴ AB = √100 = 10 cm

As we know that a rhombus has all four sides equal.

Hence side of rhombus = 10 cm.