areaofcircle

代码说明：

  一圆形游泳池如图所示，现在需在其周围建一圆形过道，并在其四周围上栅栏。 栅栏价格为35元/米，过道造价为20元/平方米。 过道宽度为3米， 游泳池半径由键盘输入。 要求编程计算并输出过道和栅栏的造价。(A circular pool as shown in figure, now in its built around to a circular corridor, and in its 4 around on the fence. The fence for 35 yuan/m price, corridor cost for 20 yuan/square metre. Aisle width is 3 meters, The radius of the swimming pool by keyboard input. Demand and output programming calculation of corridor and the cost of the fence. )