查人人中国名人网制定办法还是制订办法:Math problem
来源：百度文库 编辑：查人人中国名人网 时间：2024/05/05 22:53:05
a pond 100 feet in diameter is surrounded by a circular grass walk which is 2 feet wide. The number of square feet of grass on the walk is.....
3.14x((100+2x2)/2)^2-3.14x(100/2)^2