Given: Diameter of the base of a cone is 42 cm.

Volume of the cone is 12936 cm³.

Volume of the cone is given by: × π × r² × h

∴ × π × r² × h = 12936

⇒ × π × ()² × h = 12936 (here diameter = 42cm, ∴ r = = 21)

⇒ × π × (21)² × h = 12936

⇒ h = = 28cm

∴ Height of the given cone is 28cm