设另型态灶一闭搜圆半径为y,由单位正卜扮方形有(√为根号)。√2x+x+y+√2y=√2得y=2-√2-x则S=πx方+π(2-√2-x)方化简后S=π(2x方-(4-√2)x+6-4√2)而2(√2x-x)+2x<√2得出0