The length of a cylindrical granary is 12.56 meters, so how many square meters does the granary cover?

The length of a cylindrical granary is 12.56 meters, so how many square meters does the granary cover?

2 × 3.14 = 22 × 3.14, = 12.56 (square meters); a: This granary covers an area of 12.56 square meters