设原来圆的半径是x分米。
3.14*(x+1/5)*(x+1/5)-3.14*x*x=88
3.14*(x*x+0.4x+0.04-3.14x*x=88
3.14x*x+1.256x+0.1256=88
1.256x=87.8744
x=69.964
3.14*69.964*69.964=15370.18
设原来圆的半径是x分米。
3.14*(x+1/5)*(x+1/5)-3.14*x*x=88
3.14*(x*x+0.4x+0.04-3.14x*x=88
3.14x*x+1.256x+0.1256=88
1.256x=87.8744
x=69.964
3.14*69.964*69.964=15370.18