What is the radius of 1.5km and its diameter is 3km?

The center point extends outward 1.5km, which is the boundary; The diameter of 3 kilometers means that the distance between the farthest two points in this range is 3 kilometers. The coverage of Meituan is a circular area with its center as the center and the radius of 1.5 km, plus the whole area covered when the distance between the farthest two points in this circular area is 3 km. Can you use πr specifically? (where r= 1.5km), the circular area is about 7 square kilometers. On this basis, considering that the diameter and length should also be included, the actual coverage area should be slightly larger than 7 square kilometers.