Cut a 1 meter long cylindrical steel with a diameter of 2 decimeters into two sections and increase its surface area by () square decimeters A. 3.14B. 6.28C. 12.56

Cut a 1 meter long cylindrical steel with a diameter of 2 decimeters into two sections and increase its surface area by () square decimeters A. 3.14B. 6.28C. 12.56

2 △ 2 = 1 (decimeter), 3.14 × 1 × 1 × 2 = 6.28 (square decimeter); answer: the surface area has increased by 6.28 square decimeter