We have the diameter of a cyclindrial roller = 42 cm ⇒ The radius of cyclindrical roller (r) = 42 / 2 = 21 cm Length of a cyclindrical roller (h) = 120 cm Curved surface of the roller = 2πrh = 2 × 22 / 7 × 21 × 120 = 15840 cm2 = 15840 / 10000 m2 = 1.584 m2 Area covered by the roller in one complete revolution . = curved surface of the roller = 1.584 m2 ∴ Area of the playground = Area covered by the roller in 500 complete revolutions = 500 × 1.584 = 792 m2