英文数学选择

来源：百度知道 编辑：UC知道 时间：2024/06/04 14:07:23
1.A square pool with an area of 81 square feet is to be placed entirely within a circular enclosure with a radius of 10 feet. Tiles will be laid within the entire enclosure around the pool(but not under it). What is the approximate area, in square feet, of the enclosure that will be tiled?
A 81 B 233 C 315 D 396

一个面积为81平方英尺的正方形泳池要被完全置于一个半径为10英尺的圆圈内。圆圈里方形泳池外（泳池内不铺）的部分要铺瓷砖。请问，要铺瓷砖的面积大约多少平方英尺？
所求面积=圆的面积-正方形面积：
π*10*10-81=314-81=233
选B