通过API文档查询Math类的方法，打印如下所示的近似圆，只要给定不同半径，圆的大小随之发生改变（如果需要使用复杂的数学运算，可以查阅Math类的方法或者参考9.3节的内容）-Through the API documentation inquiries Math class methods, print as follows Approximate round, as long as give different radius, round the size of subsequent cha