Given that Volume of triangular prism = 216 cubic centimetre
Given that Height of the pencil = 12 centimetre
Now we have to find the area of the base of the prism means find the area of triangular part.
Volume of triangular prism is given by formula:
Volume of triangular prism = (Area of base) x (Height of the prism)
now plug the given values
216= (Area of the base) x 12
Area of the base
18= Area of the base
Hence final answer is 18 square centimetres.