Answer:
Lengths of the sides (there are 3 sides in an equilateral triangle) of the base of prism is 5.72cm each.
Step-by-step explanation:
As the base of triangular prism is equilateral:
∴ Area of base = (√ 3 / 4)× (side)²
According to question:
height of prism = height (side) of base
Volume of prism = 81 cm³,
∴ Volume of prism = Area of base x height
⇒  81 cm³ = (√ 3 / 4)× (side)² × height     ∵ side = height
⇒  81 cm³ = (√ 3 / 4)× (side)³
⇒  81 × (4/√3) cm³ = side³  Â
⇒  ∛(81 × (4/√3) cm = side
⇒  side = 5.72cm
