教你如何计算圆面积的小程序，简单而且易懂，初学者必备-teach you how to calculate the area of circle procedures for small, simple and easy to understand, beginners essential

圆面上的点到圆心的距离 圆 面上的点到圆心的距离 圆面上的点到圆心的距离-Round surface of the distance from point to circle center point of the surface of the distance to the center circle to the center point of the surface of the distance from the surface