reverasl of curvature

例句：

1. 1. The curved surface of the cylinder is smoother than the flat surface.
   这个圆柱体的曲面比平面更光滑。
2. 2. The radius of curvature of a circle is its diameter divided by 2.
   圆的曲率半径是直径除以2。
3. 3. The radius of curvature can be calculated using the formula r = d/2π, where d is the distance from the center to the point of interest.
   曲率半径可以通过公式r=d/2π计算，其中d是从中心到关注点的距离。